ELECTRICAL CIRCUITS

Question 1

Define Potential Dividers.

Answer 1

Simply two resistors in series that “divide” the “potential”.

Question 2

What are potential dividers used in?

Answer 2

Control circuits where you want something to happen when environmental factors change.

Power supplies e.g. when different potential differences are needed in an appliance.

Question 3

What are the equations relating to potential dividers?

Answer 3

R1/R2 = V1/V2

Vout = R1/(R1 + R2) x Vin

Question 4

Explain what happens to Vout when when the light intensity increases. (Fixed resistor is not across Vout)

Answer 4

Vout Decreases.

This as resistance of LDR will decrease.
So the total resistance in circuit will decrease.
So current in circuit will increase.
As V=IR, across fixed resistor, V will increase.
So as Vout + V = Vin, if V increases Vout decreases.

Question 5

Define Emf.

Answer 5

Energy actually provided to each unit of charge.

Question 6

Define internal resistance.

Answer 6

The hindrance to the flow of charge in the cell.

Question 7

State the equation for emf.

Answer 7

e = E/Q

Question 8

State the equation for internal resistance?

Answer 8

r = Vlost/I