Booklet 3 - Electricity (Equations)

Question 1

(Define symbols and units)

Answer 1

V_peak - Peak Voltage (V)

V_rms - rms Voltage (V)

Question 2

(Define symbols and units)

Answer 2

I_peak - Peak Current (V)

I_rms - rms Current (V)

Question 3

(Define symbols and units)

Answer 3

Q - charge (C)

I - current (A)

t - time (s)

Question 4

(Define symbols and units)

Answer 4

V - voltage (V)

I - current (A)

R - resistance (Ω)

Question 5

(Define symbols and units)

Answer 5

P - power (W)

V - voltage (V)

I - current (A)

R - resistance (Ω)

Question 6

R_T = R₁ + R₂ + ….

(What type of circuit does this apply to?

Define symbols and units)

Answer 6

This is the formula for resistance in series.

R_T - Total Resistance (Ω)

R₁ - Resistance 1 (Ω)

R₂ - Resistance 2 (Ω)

Question 7

1/R_T = 1/R₁ + 1/R₂ + ….

(What type of circuit does this apply to?

Define symbols and units)

Answer 7

This is the formula for resistance in parallel.

R_T - Total Resistance (Ω)

R₁ - Resistance 1 (Ω)

R₂ - Resistance 2 (Ω)

Question 8

(Define symbols and units)

Answer 8

E - emf (V)

V - terminal potential difference (V)

I - current (A)

r - internal resistance (Ω)

Question 9

(Define symbols and units)

Answer 9

V₁ - Voltage across resistor 1 (V)

R₁ - Resistance of resistor 1 (Ω)

R₂ - Resistance of resistor 2 (Ω)

V_s - Supply Voltage (V)

(NB it doesn’t matter which resistors you choose to call 1 and 2 as long as you are consistent in labelling the voltages in the same way i.e. V₁ across R₁, V₂ across R₂)

Question 10

(Define symbols and units)

Answer 10

V₁ - Voltage across resistor 1 (V)

V₂ - Voltage across resistor 2 (V)

R₁ - Resistance of resistor 1 (Ω)

R₂ - Resistance of resistor 2 (Ω)

(NB it doesn’t matter which resistors you choose to call 1 and 2 as long as you are consistent in labelling the voltages in the same way i.e. V₁ across R₁, V₂ across R₂)

Question 11

(Define symbols and units)

Answer 11

C - capacitance (F)

Q - charge (C)

V - voltage (V)

Question 12

(Define symbols and units)

Answer 12

E - energy (J)

Q - charge (C)

V - voltage (V)

C - capacitance (F)