Physics 10 Chapter 15 - Electromagnetism - 17

Physics 10 Chapter 15 - Electromagnetism - 17

1. A transformer, designed to convert the voltage from 240 V A.C. mains to 12 V, has 4000 turns on the primary coil. If the transformer were 100% efficient, what current would flow through the primary coil when the current in the secondary coil was 0.4 A?

a) 0.002 A
b) 0.02 A
c) 2 A
d) 0.2 A

1. A transformer, designed to convert the voltage from 240 V A.C. mains to 12 V, has 4000 turns on the primary coil. If the transformer were 100% efficient, what current would flow through the primary coil when the current in the secondary coil was 0.4 A?

a) 0.002 A
b) 0.02 A
c) 2 A
d) 0.2 A

3. The turn ratios of a transformer are 20. What does it mean?

a) Vs = Vp /20
b) Ns = 20Np
c) Ns = Np /20
d) Is = 20Ip

4. Step up transformer decreases value of..................?

a) Current
b) Force
c) Resistance
d) Voltage

5. If a transformer is used to supply voltage to a 12 V model train which draws a current of 0.8 A. Calculate the current in the primary if the voltage of the a.c. source is 240 V?

a) 4 A
b) 0.04 A
c) 0.004 A
d) 0.4 A

6. Step down transformer increases value of..................?

a) Force
b) Current
c) Voltage
d) Resistance

7. A power station generates 500 MW of electrical power which is fed to a transmission line. What current would flow in the transmission line if the input voltage is 250 kV?

a) 2 x 10^-3 A
b) 2 x 10³ A
c) 2 x 10^-2 A
d) 2 x 10² A

8. At the city sub-station, voltage is further stepped down to how many voltages?

a) 2200 V
b) 200 V
c) 202 V
d) 220 V

9. Usage of transformer is common because they change voltage with relatively ....................loss of energy?

a) Very much
b) More
c) Little
d) Zero

10. Heat dissipated in the transmission cable of resistance R is..................?

a) I^-3Rt
b) I^-2Rt
c) I²Rt
d) I³Rt

This is more feedback!

This is the feedback!