Rosshall Academy Physics Department s1

Rosshall Academy Physics Department Name:

Term 3 Week 6 Homework

General

1.  The diagram below shows the system used to send electrical energy from a power station to a home.
(a) Identify the parts labelled Y and Z.
Part Y
Part Z
(b) Why are very high voltages used in the transmission of electrical energy?
(c) State whether the 275 000 volts used in the transmission line is alternating voltage or direct voltage.
(d) The power station in the above diagram uses coal as the fuel. Name the energy transformation which takes place when coal is burning.
(e) State the size of the voltage used to transmit electricity between Z and the home.

2.  On a cold winter’s day, heat is lost through the walls of a house. Houses can have different types of wall as shown below, depending on how they were built.
The table below shows the ways in which heat is lost by the different types of wall. H-lots of heat loss M - medium heat loss L - little heat loss

(a) From all the information given above, match the type of wall with the walls labelled A, B and D. Enter your answers to complete the table below.

(b) Wall C is the only one which has a low heat loss by radiation. Explain.

Credit

1. Mary is sitting in the crowd at a rock concert being held at Wembley stadium in London. Mary’s seat is 150 m from the loudspeakers as shown. Her brother John is listening to a live broadcast of the concert on his personal radio in their Edinburgh home.
   (a) Explain why John hears the music before Mary.
   (b) Calculate how far radio waves will travel in the time it takes the sound from the speakers to reach Mary.
   (c) The concert is being broadcast on both the medium wave and FM radio
   wavebands. FM radio waves have higher frequencies than the radio waves used on the medium waveband.
   (i) In which of these wavebands do the radio waves have the longer wavelength?
   (ii) Explain why people who live in hilly country may have no choice but to listen to the medium wave broadcast of the concert, even if their radios are designed for both medium wave and FM.
   
   
2. The diagram below shows a simplified version of the wiring used for a car’s sidelights and headlights. The negative terminal of the battery is connected to the metal body of the car at Z.
   The sidelights of the ear are rated at 12 V, 6 W and the headlights at12 V,
   48 W.
   (a) Which lights are switched on by closing:
   (i) switch S1 only;
   (ii) both switches S1 and S2?
   (b) Calculate the current in one of the headlights when it is switched on.
   

General Mark /10 Grade
Credit Mark /10 Grade
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