COE/DC

Question 1

Electric current is

Answer 1

The rate of flow of charge

Question 2

Formulas for current (there are 2)

Answer 2

Q/t

nAVdq

Question 3

Potential difference between two points in a circuit is

Answer 3

The amount of electrical energy per unit charge converted to other forms of energy when charge passes from one point to another

Question 4

One volt is

Answer 4

The potential difference between two points in a circuit when one joule of electrical energy as one coloumb of charge passes from one point to another

Question 5

formula for volt

Answer 5

V - W/Q

Question 6

Electromotive force of a source is

Answer 6

The amount of electrical energy per unit charge that is converted from other forms of energy when the source drives a unit charge around a complete circuit.

Question 7

Formula for electromotive force

Answer 7

E = W/Q

Question 8

Power is

Answer 8

The rate at which work is done

Question 9

Formula for power

Answer 9

W = IV = I^2R = V^2/R

Question 10

Resistance is

Answer 10

The ratio of the potential difference across the object to the current flowing through it

Question 11

The Ohm is

Answer 11

The resistance of a conductor when a potential difference in a conductor is proportional to the electric current passing through it, provided its temperature remains constant.

Question 12

Ohm’s law

Answer 12

The potential difference in a conductor is proportional to the electric current passing through it, provided its temperature remains constant.

Question 13

Formula for resistivity of a wire

Answer 13

R = pA/l so p = Rl/A

Question 14

Define resistivity of a wire

Answer 14

• The property of a material to oppose electric current.
• The constant of proportionality that relates resistance of a component to it’s length to cross sectional area ratio.
• Constant at a certain temperature, independent of dimensions.

Question 15

Series arrangement

Answer 15

I1 = I2 = I3
E = V1 + V2 + V3
R = R1 + R2 + … + Rn

Question 16

Parallel arrangement

Answer 16

I = I1 + I2 + I3
E = V1 = V2 = V3
R is that one complicated to type formula

Question 17

How does a Thermistor work

Answer 17

Resistance DECREASES when temperature INCREASES

Question 18

How does an LDR work

Answer 18

Resistance DECREASES when light intensity INCREASES

Question 19

One coloumb is

Answer 19

The amount of electric charges that passes through a point in one second when there is a constant current of one ampere.

Question 20

Derive the current carried by a conductor, I = nAvdq

Answer 20

I = ΔQ/Δt = (ΔN)q/Δt = (nΔv)q/Δt = (nAΔx)q/Δt = nAVdq

Question 21

Derive power (electrical derivation)

Answer 21

P = dW/dt = d(QV)/dt = dQ(V)/dt = IV

Question 22

Derivation of resistance in series circuits

Answer 22

IE = I² (R1 + R2 + R3)
E = I (R1 + R2 + R3)
E = V1 + V2 + V3
ΣE = ΣV = ΣIR
IReff = IR1 + IR2 + IR3
Reff = R1 + R2 + R3