The a.c. generator

Fig. 6.1 shows a basic a.c. generator. The diagram labels are: coil, N pole, S pole, rotation of coil, and output voltage. Fig. 6.2 shows how the alternating e.m.f. varies with time.

May/June 2015

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

May/June 2018

Which method for generating electricity does not make use of an a.c. generator?

May/June 2019

A coil is turning within a magnetic field. The coil is attached to an oscilloscope. The diagram shows the trace displayed on the oscilloscope screen. The coil then increases its speed and turns at twice the original rate. Which diagram shows the updated trace?

May/June 2019

The diagram illustrates a generator. What do X and Y represent?

May/June 2024

An alternating current (a.c.) generator is linked to an oscilloscope. The diagram illustrates the trace that appears on the oscilloscope screen. What possible angles could there be between the plane of the coil and the direction of the magnetic field at the instants shown by points 1, 2 and 3?

May/June 2025

Which equation represents the efficiency of an a.c. generator?

Oct/Nov 2016

What is combined with a magnet to produce an induced electromotive force (e.m.f.) in a simple a.c. generator?

Oct/Nov 2020

The diagram illustrates the output from an a.c. generator as it appears on an oscilloscope screen. The generator is then rotated more slowly. The oscilloscope control settings are left unchanged. Which diagram shows the new output?

Oct/Nov 2022

A wire coil is turned at a steady speed between the poles of a U-shaped magnet. Each end of the coil is joined to a separate slip ring. Which graph shows the way the voltage $V$ between the slip rings changes with time $t$?

Oct/Nov 2022

Which graph represents the voltage output plotted against time for a simple a.c. generator?

Oct/Nov 2023

The output from an a.c. generator is connected to a lamp. The generator coil is turned at a steady rate, causing the lamp to flash twice each second. The coil is then turned at half this rotational rate. What happens to the lamp’s maximum brightness, and how many times per second does the lamp flash?

Oct/Nov 2023

An a.c. generator is installed in a remote area to provide electricity. Fig. 7.1 illustrates the layout of a simple a.c. generator with the coil drawn horizontally. The diagram labels the output terminals, P, Q, N, S, the horizontal coil and the direction of rotation.

Oct/Nov 2023