Science Form 3 - Electricity and Magnetism

Power stations that use wind energy do not contaminate the air

• True

• False

Solar cells can produce alternating current

• True

• False

2-pin plugs are not connected to the earth wire

• True

• False

Coal is a (a)   energy source

Biomass, wave and geothermal are all (a)   energy sources.

Figure 2(b) and 2(c) show two traces traces displayed on the screen of cathode ray oscilloscope.

Name the type of electric current represented by the trace on the screen in Figure 2(b).

(a)  

Figure 2(b) and 2(c) show two traces traces displayed on the screen of cathode ray oscilloscope.

Name the type of electric current represented by the trace on the screen in Figure 2(c).

• Alternating current

• Direct current

Figure 3 shows a type of transformer.

Name the type and give a reason why.

• Step-down transformer because the number of coils in primary coil is more than secondary coil

• Step-up transformer because the number of coils in primary coil is more than secondary coil

• Step-down transformer because the number of coils in primary coil is less than secondary coil

• Step-up transformer because the number of coils in primary coil is smaller than secondary coil

If the number of turns in the primary
coil is 100 and the number of turns in
the secondary coil is 20,
calculate the
secondary voltage if the primary voltage
is 10 V.
(use the formula given)

(a)  

What is the suitable fuse rating of a hair dryer rated 700 W, 240 V?

• 1 A

• 3 A

• 5 A

• 13 A