8 - electric resistance

Question 1

know and use the relationship between voltage, current and resistance

Answer 1

V = I x R

Potential difference (V) = Current (Amps) x Resistance (Ω)

Question 2

what does the current in a series circuit depend on… the applied voltage and the number and nature of other components

Answer 2

it depends on: the applied voltage and the number and nature of other components

-As voltage increases the current also increases.
- In general, the more components in a circuit, the lower the current.

Question 3

describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how to investigate this experimentally

Answer 3

in the bellow diagram the red box could represent a wire, a bulb, a resistor or a diode.

By changing the resistance of the variable resistor the graphs are reproduced.

Question 4

describe the qualitative effect of changing resistance on the current in a circuit

Answer 4

Since V = IR, as you increase the resistance in a circuit, the current will decrease.

Question 5

describe the qualitative variation of resistance of light-dependent resistors (LDRs) with illumination and thermistors with temperature

Answer 5

LDR: as illumination increases, resistance decreases

Thermistor: As temperature increases, resistance decreases.

Question 6

2.19 calculate the currents, voltages and resistances of two resistive components connected in a series circuit

Answer 6