Electricity and Electronics

Question 1

What happens when you increase the length of a transmission cable?

Answer 1

Resistance increases proportional to length.

This increases energy losses in cables due to heating.

Question 2

What happens to wavefronts when you add a diode?

Answer 2

1. Becomes half-wave
2. Amplitude reduced by 3/4 original
3. Same wavelength

Question 3

What happens to a lamp when you introduce the diode into a circuit, and why?

Answer 3

Lamp turns on and off

Due to current becomes 0 half the time

Question 4

What are the benefits and cost of constructing cables with a higher area?

Answer 4

Benefit: decreases resistance and thus heat loss
Costs: Increased cost of construction, cables are heavier

Question 5

Draw magnetic field in a solenoid.

Answer 5

Include 4 magnetic lines outside coil
Include 2 magnetic lines inside coil
Never cross

Question 6

What equipment do you need to use to measure induced current?

Answer 6

A galvanometer

Question 7

What happens to the frequency of current in a transformer?

Answer 7

It stays the same frequency

Question 8

What happens when p.d. across a resistor increases?

Answer 8

P.d across the rest of the circuit decreases