May/June 2018

Which of the following statements about electromagnetic waves is correct?

Electromagnetic spectrum

Four objects, all with equal mass, are resting on a table. For each object, its centre of mass is shown by G. Which object is the least stable?

Centre of gravity

Forces of $4.0\,\text{N}$ and $2.0\,\text{N}$ act at one point. Which scale diagram shows forces with a resultant of $4.0\,\text{N}$?

Balanced and unbalanced forces

A student works out his power when running up a staircase. He measures the vertical height of the stairs, the time taken to run up them and his weight. How does he calculate his power?

Power

In what way is an oil-fired power station different from a nuclear power station?

Energy resources

Five blocks each have the same mass, but their base areas are different. They are all placed on a horizontal table. A graph is drawn to represent the link between the pressure exerted on the table and the block's base area. Which graph represents this link?

Pressure

For a car, each tyre has $100\,\text{cm}^2$ of contact area with the ground. The car’s mass is $1600\,\text{kg}$. Its weight is shared equally by the four tyres. The gravitational field strength $g$ is $10\,\text{N kg}^{-1}$. What pressure is applied to the ground?

Pressure

The diagram illustrates a basic mercury barometer. Which height indicates the atmospheric pressure?

Pressure

What is meant by ‘the escape of the more energetic molecules from a liquid surface’?

Melting, boiling and evaporation

The diagrams show four thermometers. Which thermometer has the highest sensitivity, and which one has the largest range?

Thermal expansion of solids, liquids and gases

What happens to a solid when heating causes it to expand?

Thermal expansion of solids, liquids and gases

A student wants to measure the circumference of a football directly. Which instrument would be the most suitable to use?

Physical quantities and measurement techniques

When a piece of smouldering rope is placed at the opening of the box shown in the diagram, the smoke travels in the direction shown. What causes the smoke to move?

Convection

The diagrams illustrate four identical cans, each with an outside surface that is either polished silver or coated dull black. Every can holds the same volume of water, starting at 80^{\circ}C. Following five minutes in a cool room, which can will have the water at the lowest temperature?

Radiation

The diagram illustrates two spreading rays of light from an object O after they are reflected by a plane mirror. In which location is the image produced?

Reflection of light

Which of the following statements is correct?

Physical quantities and measurement techniques

The diagram illustrates the routes taken by two rays from the top of an object passing through a lens. The image is seen from the side of the lens opposite the object. In what ways is the image different from the object?

Thin lenses

A person who has healthy ears at a young age can detect a span of frequencies. What is the approximate frequency range?

Sound

The diagram illustrates a loudspeaker emitting a continuous sound wave of frequency 200 Hz in air. Which diagram most accurately shows how the sound wave makes a molecule at P move in $\frac{1}{200}\text{ s}$?

Sound

The diagram illustrates an alarm system. What occurs when battery P is disconnected?

Action and use of circuit components

In a wire, an electric current is directed into the page. Which diagram illustrates the pattern and direction of the magnetic field surrounding the wire?

Magnetic effect of a current

Copper wire X has resistance $R$. A second copper wire, Y, is twice as long and has half the cross-sectional area of X. What is the resistance of Y?

Resistance

The diagram represents a satellite $S$ moving at constant speed in a circular orbit about a planet $P$. Which statement is correct?

Circular motion

In the circuit shown, the room temperature and the light intensity influence the current. Under which conditions is the current in the circuit greatest?

Action and use of circuit components

An electrical appliance is connected to a wall socket. The plug has a fuse. What is the fuse’s main purpose?

Electrical safety

A horizontal beam of electrons travels between the two poles of a magnet. Which direction does the beam deflect?

Forces on a current-carrying conductor

Which graph shows voltage output $V$ plotted against time $t$ for an a.c. generator?

The a.c. generator

A loudspeaker and a microphone are positioned in front of a wall. The loudspeaker produces a sound that is picked up by the microphone. The microphone is linked to an oscilloscope, which is adjusted so that one division on the screen corresponds to $0.01\,\text{s}$. The microphone detects both the initial sound and the echo. The speed of sound in air is $300\,\text{m s}^{-1}$. What is the separation between the loudspeaker and the wall?

Sound

In the circuit diagram, a variable resistor $R$ is connected in parallel with the lower section of a potential divider. The resistance of $R$ rises. What effect does this have on the two voltmeter readings?

Series and parallel circuits

Thin aluminium foil is used for cooking. The diagram shows an arrangement used to regulate the thickness of aluminium foil produced in a factory. What is the most suitable radioactive source for the system?

Detection of radioactivity

Of alpha, beta and gamma radiations, which are waves?

The three types of emission

One radioactive isotope of hydrogen has a half-life of $12\text{ years}$. A sample contains $40$ million atoms of this isotope. How many atoms of this isotope remain after $24\text{ years}$?

Half-life

How many nucleons are present in a single neutral atom of the krypton isotope $^{{84}}_{{36}}\text{Kr}$?

The nucleus

Which speed-time graph shows the motion of a railway train that makes a brief stop at a station?

Motion

A radioactive nucleus is shown as $^{{230}}_{{92}}\text{U}$. Which row shows a different isotope of this same element?

The nucleus

A car’s minimum braking distance is measured on a dry road surface. The same test is then carried out again on a wet road. What happens to the braking distance and to the frictional force between the tyres and the road?

Friction

What piece of equipment is used for measuring mass?

Mass and weight

A body of mass $10\,\text{kg}$, when falling freely in the Moon’s gravitational field near its surface, has an acceleration of $1.6\,\text{m s}^{-2}$. What is the value of the gravitational field strength on the Moon?

Mass and weight

The graph illustrates extension-load curves for four fibres. Which fibre is hardest to stretch across the range of loads shown?

Elastic deformation

The diagram represents a muscle and the bones in a person’s arm. The hand is supporting a load with weight $40\,\text{N}$. The elbow serves as the pivot, and the muscle tension keeps the forearm horizontal. What is the tension in the muscle caused by the load?

Turning effect of forces

Which quantity has both magnitude and direction?

Physical quantities and measurement techniques

Two objects X and Y hang from a uniform rod that is pivoted at its centre. The rod is balanced. Which statement about X and Y is correct?

Turning effect of forces

A force of $1600\,\text{N}$ causes a car of mass $800\,\text{kg}$ to speed up from rest. What are the car’s acceleration and its velocity after $4.0\,\text{s}$?

Balanced and unbalanced forces

The graph plots extension-load curves for four fibres. Across the range of loads shown, which fibre is the most difficult to stretch?

Elastic deformation

Four objects, each with the same mass, are placed at rest on a table. The centre of mass of every object is marked $G$. Which object has the lowest stability?

Centre of gravity

Which power station releases carbon dioxide during operation?

Energy resources

A force of $400\,\text{N}$ pulls a crate with weight $500\,\text{N}$ up a ramp at constant speed, as illustrated. Some of the work done raises the crate’s gravitational potential energy $E$, while the remainder is work done $W$ against friction. What are the values of $E$ and $W$?

Work

There are five blocks, each with the same mass but with different base areas, and all are placed on a horizontal table. A graph is drawn to illustrate how the pressure on the table varies with the block’s base area. Which graph represents this relationship?

Pressure

The diagram depicts a simple mercury barometer. Which height provides a measure of atmospheric pressure?

Pressure

A sealed packet that contains air and a snack is bought at an airport. The sealed packet is then carried onto an aircraft. During the flight, the packet gets bigger. What causes the packet to get bigger?

Pressure

A closed container of gas is warmed, causing the pressure inside to rise. What happens to the gas molecules that leads to this rise in pressure?

Particle model

Two forces, $4.0\,\text{N}$ and $2.0\,\text{N}$, act at a point. Which scale diagram represents the forces whose resultant is $4.0\,\text{N}$?

Forces

Equal masses of copper and water are heated to the same temperature. When they cool, the copper and the water lose thermal energy at the same rate. The copper’s temperature drops more quickly. What is the reason for this?

Specific heat capacity

The diagram shows a thermometer. What substance is present in region X of the capillary tube?

Thermal expansion of solids, liquids and gases

The diagrams show four thermometers. Which thermometer has the highest sensitivity and which thermometer has the widest range?

Thermal properties and temperature

The resistance $R$ of a wire rises in direct proportion to temperature. The table gives the values of $R$ at the fixed points: when the temperature is $0^\circ$C, $R = 100\,\Omega$; when the temperature is $100^\circ$C, $R = 250\,\Omega$. At what temperature does $R = 160\,\Omega$?

Resistance

Four samples of different materials at room temperature are heated from underneath, and heat moves upward. In which material is all of the heat carried by molecular vibration?

Conduction

The diagrams depict four identical cans whose outer surfaces are either polished silver or coated dull black. Each can holds the same volume of water, which starts at $80^\circ$C. After five minutes in a cool room, which can has the coolest water?

Radiation

A communications system employs microwaves that have a wavelength of $15\,$cm. The speed of light is $3.0 \times 10^8\,\text{m s}^{-1}$. What is the frequency of these microwaves?

Electromagnetic spectrum

The diagram illustrates two diverging light rays from an object O after they have reflected off a plane mirror. In which position is the image produced?

Reflection of light

Which statement about blue light is right?

Electromagnetic spectrum

Which device operates by total internal reflection?

Refraction of light

What is the unit name and numerical value represented by mW?

Power

A television remote control sends out an infra-red beam. Which statement concerning infra-red radiation is correct?

Electromagnetic spectrum

The diagram shows a loudspeaker emitting a continuous sound wave with frequency $200\,$Hz in air. Which diagram most accurately shows the motion of a molecule at P caused by the sound wave during $\frac{1}{200}\,$s?

Sound

Which frequency lies within the hearing range of a healthy human ear?

Sound

State one use of ultrasound.

Sound

The diagram illustrates an alarm system. What occurs when battery P is disconnected?

Electric circuits

$V$ represents potential difference, $I$ represents current, $R$ stands for resistance, and $t$ denotes time. Which expression has the units of energy?

Electrical quantities

A step-down transformer contains a primary coil and a secondary coil wrapped around a soft-iron core. The primary coil is linked to a $6.0\,\text{V}$ direct current (d.c.) supply. Which statement about the transformer is correct?

The transformer

Which symbol is used to represent a light-dependent resistor?

Circuit diagrams and circuit components

In the circuit diagram, a variable resistor $R$ is connected in parallel with the lower section of a potential divider. The resistance of $R$ increases. What happens to the two voltmeter readings?

Action and use of circuit components

An oscilloscope is used to measure potential difference (p.d.). The trace with nothing connected to the input is shown. A $1.5\,\text{V}$ d.c. supply is connected to the oscilloscope. The Y-gain is set at $0.5\,\text{V/div}$. The time-base is set at $0.5\,\text{ms/div}$. Which trace shows a supply of $1.5\,\text{V}$ d.c.?

Uses of an oscilloscope

Micrometers, metre rules, tapes and calipers are all instruments used to measure length. Which row shows the device most suitable for measuring the specified length accurately?

Physical quantities and measurement techniques

In one neutral atom of the krypton isotope $^{84}_{36}\text{Kr}$, how many nucleons are present?

The nucleus

The planets in the Solar System travel around the Sun. Which statement is correct?

The Solar System

Which forces are acting on a skydiver as they fall at terminal velocity?

Balanced and unbalanced forces

A uniform rod with weight $5.0\,\text{N}$ is first kept at rest. The diagram indicates the forces acting on the rod at the moment it is let go. What occurs to the rod when it is released?

Turning effect of forces

A metal block is put on an electronic balance so that its mass can be measured. What unit is used for the balance reading, and what unit is used for weight?

Mass and weight

A $10\,\text{kg}$ body is in free fall near the Moon’s surface and its acceleration is $1.6\,\text{m s}^{-2}$. What is the Moon’s gravitational field strength?

Mass and weight

A cyclist is moving on a straight, level road, as illustrated in Fig. 1.1.

Motion

Describe two ways in which boiling and evaporation differ.

Melting, boiling and evaporation

A water wave is generated in a ripple tank.

General properties of waves

Fig. 2.1 shows a man pushing a heavy box using a force $P$. A frictional force $F$ acts in the horizontal direction.

Balanced and unbalanced forces

As shown in Fig. 3.1, a passenger on an aircraft seals a plastic bag that contains air.

Particle model

A woman is doing work while lifting a flag by pulling the rope downwards. This is illustrated in Fig. 4.1.

Work

A student has three resistors, and each one is labelled $3.9\,\Omega$, $3\,\text{W}$. She is checking the resistance of one of them.

Circuit diagrams and circuit components

A steel rod is magnetised by means of an electrical technique.

Magnetic effect of a current

Electrostatics may be a nuisance, but it is also useful.

Electrical charge

Fig. 8.1 depicts a transformer that links an overhead $25\,000\,\text{V}$ power line to a house.

The transformer

The Sun emits electromagnetic radiation, and that radiation then travels from the Sun to the Earth.

Dispersion of light

A student releases a small metal object into a cylinder of oil. As it moves down beside a vertical ruler, a camera records its position at 1.0 s intervals, as shown in Fig. 1.1.

Motion

A student links a battery to two resistors. The circuit diagram appears in Fig. 10.1. The potential difference (p.d.) across the 40 Ω resistor is 9.6 V.

Electromotive force and potential difference

A smoke detector holds a tiny radioactive source of americium-241. This source gives out alpha-particles.

Radioactivity

In this experiment, a student records measurements and finds the extension of a spring for a range of loads. The arrangement is shown in Fig. 2.1. The results are given in the table in Fig. 2.2.

Elastic deformation

Metal, water and air, each with the same volume, are heated from 20 ^{\circ}C to 80 ^{\circ}C.

Thermal expansion of solids, liquids and gases

Latent heat is the thermal energy required to change a solid into a liquid.

Melting, boiling and evaporation

A microwave signal is sent from a transmitter on the Earth’s surface to a satellite in orbit, and it is then sent straight back to Earth.

General properties of waves

A converging lens has a focal length of 3.0 cm. An object that is 2.0 cm tall is positioned 5.0 cm from the centre of the lens. Fig. 6.1 displays the object and lens setup.

Thin lenses

A computer hard disk has a layer made of magnetic material.

Electromagnetic induction

A fuse is one type of protection used in an electrical circuit.

Electrical safety

Wind energy is a renewable energy source. A wind turbine and generator convert the energy in the wind into electrical energy. Fig. 9.1 shows some wind turbines.

Energy, work and power

A student is given two metal rods: one is copper and the other is iron. She carries out an experiment to find out which metal conducts heat better. She places the rods across a heat-proof mat on a tripod stand, with the rods touching at one end, as shown in Fig. 1.1. At the other end of each rod, she attaches a drawing pin using a small blob of wax that has a low melting point. She then heats the ends where the rods touch, as shown.

Conduction

A student has two identical springs. He hangs them from a thin metal bar that is kept in a horizontal position between two stands.

Elastic deformation

Fig. 3.1 shows a jar containing 50 small glass beads that vary in size and shape.

Density

A student determines the refractive index $n$ of a rectangular glass block. Fig. 4.1 shows one face of the block. The student follows the route taken by a ray of light as it enters the block at side AB and leaves it at side CD.

Refraction of light

A student finds the resistance of a lamp for different currents flowing in the lamp. She arranges the circuit shown in Fig. 1.1.

Resistance

A student carries out an investigation into the reflection of light from a plane mirror. She stands the mirror upright on a sheet of paper, marks the mirror’s position with a straight line called XY, removes the mirror and draws a normal at the midpoint of the line called AC, then labels the point where the normal crosses the mirror as B.

Reflection of light

A student determines the minimum pressure that a rectangular wooden block applies to a table.

Pressure

A student is working out the density of copper by using a balancing method. The apparatus is arranged as shown in Fig. 4.1.

Density