Electricity

Question 1

What is the definition of Voltage

Answer 1

V = I x R

The work done in moving 1C of charge

Question 2

what is the definition of current

Answer 2

I = V/R

The charge that flows per second

Question 3

What is the definition of EMF

Answer 3

Total work done by moving 1C of charge through a battery and around the circuit

ε = I (R + r)

Question 4

What is a superconductor

Answer 4

A metal that has a resistance of 0 at and below a critical temperature

Question 5

What is internal resistance ?

Answer 5

Resistance of materials inside a battery

Question 6

What does the graph of I-V for a resistor look like ?

Answer 6

Straight line,
high gradient - low R
low gradient - high R

Question 7

What is the I-V curve for a bulb

Answer 7

As V increases, so does I
Mirrored into negative quadrant

Question 8

What happens to an LDR as it gets lighter ?

Answer 8

Increase in resistance

Question 9

What happens to a thermistor as it gets hotter ?

Answer 9

The resistance decreases

Question 10

What are the rules for V, R and I in a series circuit ?

Answer 10

R : adds up

V : adds up

I : the same everywhere

Question 11

What are the rules for R, V and I in a parallel circuit ?

Answer 11

R: 1/R1 + 1/R2 + 1/R3 …… = 1/RT

V: the same everywhere

I: adds up

Question 12

What are the potential divider equations ?

Answer 12

V/Vt = R/Rt

R1/R2 = V1/V2

Question 13

What is the graph for EMF ?
E = V + Ir
E = IR + Ir

Answer 13

V against I
E is y intercept
-r is gradient

y = mx + c
V = -Ir + E

Question 14

What is a diode’s positive threshold voltage ?

Answer 14

0.6 V

Question 15

What is a diode’s breakdown value ?

Answer 15

-50 V