Current Electricity-chap 21,22,23

Question 1

Electric current definition

Answer 1

A flow of electric charges

Question 2

Electric current definition

Answer 2

amount of charge passing a point every second

Question 3

current definition

Answer 3

movement of electrons

Question 4

Emf definition

Answer 4

The voltage between two ends of a circuit when no current is flowing in the circuit

Question 5

Give three sources of Emf

Answer 5

Electric cells
Simple cell
Primary and Secondary cells

Question 6

Explain electric cells

Answer 6

Convert chemical energy to electrical energy. Consists of two metals- the electrodes immersed in a substance called electrolyte

Question 7

Explain simple cell

Answer 7

Cu plate and Zn plate in a beaker of dilute sulfuric acid, the acid reacts with the plates, Cu plate becomes positively charged, Zn plate becomes negatively charges

Question 8

Explain primary and secondary cells

Answer 8

Primary cell- cannot be recharged, once the chemicals are used up
Secondary cell- can be recharged by pushing current in the wrong direction

Question 9

State Ohm’s law

Answer 9

states that for a metallic conductor at constant temperature, the current flowing through the conductor is directly proportional to the potencial difference across the conductor

Question 10

Thermistor definition

Answer 10

semiconductor whose resistance decreases rapidly with increasing temperature