HDE Section 1: Calculating current and potential difference (Electric Circuits)

Question 1

Calculate the resistance when the potential difference is measured as 20 V and the current is measured as 450 mA.
Over a 2.0 minute period, calculate the number of electrons flowing past the point.

Answer 1

1) V=IR
20 = I x 0.45
20 / 0.45 = 44.4

2) I = Q/t
0.45 = Q / (2 x 60)
0.45 x 120 = Q
Q = 54
Q / e = 3.375 x 10^20

Question 2

The total potential difference across the resistors in series is?

Answer 2

The sum of the potential differences across the separate resistors: VT = V1+ V2+ V3

Question 3

The current through each resistor in series is what?

Answer 3

The current through each resistor in series is the same.

Question 4

The total resistance in series is?

Answer 4

Is the sum of separate resistors: RT = R1 + R2 + R3

Question 5

The potential difference across each resistor in parallel is?

Answer 5

The potential difference across each resistor in parallel is the same.

Question 6

The current in the main circuit what in parallel?

Answer 6

Split

The current in the main circuit is the sum of the currents in each of the parallel branches: IT = I1 + I2 + I3