4.2 Energy Power Resistance

Question 1

Potential Difference

Answer 1

The energy transferred from electrical energy into other forms, per unit charge.

Question 2

Electromotive Force

Answer 2

The energy transferred from chemical energy to electrical energy per unit charge.

Question 3

Ohm’s Law

Answer 3

For a metallic conductor kept at constant temperature, the current in the wire is directly proportional to the potential difference across it.

Question 4

What will the IV characteristic graph of any ohmic component have?

Answer 4

A constant linear gradient.

Question 5

Some components are non-ohmic. Why?

Answer 5

When the current across the component increases, the metal ions are heated, gaining kinetic energy. They collide more frequently with electrons so more work is done on the charge carriers, increasing resistance.

Question 6

Filament lamp. Ohmic or non ohmic?

Answer 6

Ohmic for small current values.
Non-ohmic for large current values

Question 7

Diode

Answer 7

Semiconductor component that allows current to flow in one direction.

Question 8

NCT Thermistor

Answer 8

Non-ohmic semiconductor component. As temperature increases, resistance decreases.

Question 9

Light Dependant Resistor

Answer 9

Non-ohmic semiconductor component. As light intensity increases, resistance decreases.

Question 10

Resistivity Unit

Answer 10

Ohm-meters

Question 11

Determining resistivity of wire

Answer 11

Record cross-sectional area of wire
Record length of wire
Setup circuit with wire, voltmeter, ammeter
Record pd and current to determine resistivity of the wire’s material.