Physics 5054 · O Level · Energy, work and power

Energy, work and power — practice question

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.
(a(i))[1]

State the meaning of a renewable energy source.

(a(ii))[1]

State the name of one further renewable energy source.

(a(iii)-1)[1]

State one method of generating electricity that produces a large amount of global warming.

(a(iii)-2)[1]

Describe, in outline, how the method you have chosen leads to a significant amount of global warming.

(b(i))[2]

Calculate the kinetic energy of the air entering the turbine in 30 minutes.

(b(ii))[2]

Calculate the electrical energy delivered by the turbine in 30 minutes.

(b(iii))[2]

Calculate the efficiency of the turbine and generator in changing the kinetic energy of the air into electrical energy.

(c(i))[2]

On the grid in Fig. 9.2, sketch a voltage-time graph to show the output voltage.

(c(ii)-1)[2]

Explain why electrical energy is transmitted at a high voltage.

(c(ii)-2)[1]

Explain why a transformer is needed between the transmission line and the house.

Worked solution & mark scheme

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