Yr 12 - Charge & Current - 2

Question 1

Ohms Law

Answer 1

Potential difference across a conductor is directly proportional to the current given the temperature remains constant.

• Resistance constant at constant temperature

Question 2

Resistance equation (Not VIR)

Answer 2

Resistance (Ω) = PD across a component (V) / Current in the component (A)

Question 3

Ohm Defintion

Answer 3

Resistance of component with PD = 1v per ampere of current

1 Ω = 1V / 1A

Question 4

Relationship between resistance and temperature

Answer 4

Resistance is directly proportional to temperature

Question 5

Current-Potential Difference graph:

• Resistor (Ohmic conductor)
• Filament bulb
• Diode

Answer 5

Resistor: Straight line y=x

filament bulb: slanted s shape through origin

Diode: Straight line until origin, then exponential curve

Question 6

Threshold Voltage

Answer 6

Greatest value where no current is flowing (Diode graph)

Question 7

How do you find the resistance from a I-V graph?

Answer 7

V / I

Question 8

LDR

Answer 8

Component with resistance ∝ 1 / Light intensity

• Photoconductive
• Made of semi-conductors (Due to ability to change resistance)

Question 9

What does photoconductive mean?

Answer 9

Photos emitted (light) hit surface, liberating charge carriers resulting in greater current and lower resistance.

(Due to VIR, less current flowing per second therefore greater resistance)

Question 10

Conductance and resistance relationship.

Answer 10

Conductance directly proportional to resistance.

Question 11

How to find total resistance:

• Parallel
• Series

Answer 11

Parallel: 1/R Total = 1/R1 + 1/R2 . . .

Series: R Total = R1 + R2 . . .