Chapter 2: Current Electricity

Question 1

Physical quantity

Answer 1

A quantity that can be measured - consists of magnitude and unit

Question 2

Derived quantity

Answer 2

A quantity obtained from two or more physical quantities

Question 3

Conventional current

Answer 3

Current flows from the positive terminal to the negative terminal

Question 4

Electrons flow

Answer 4

Current flows from the negative terminal to the positive terminal

Question 5

Current

Answer 5

The rate of flow of charges

Measure with ammeter - in series

Question 6

Electromotive force - EMF

Answer 6

Work done by a source to drive one unit charge around a complete circuit

Measure with voltmeter in parallel

Question 7

Potential difference - P.D.

Answer 7

Work done to drive a unit charge through a component or between two points in a circuit

Measure with voltmeter in parallel

Question 8

Resistance

Answer 8

A measure of how difficult it is for a current to flow through a component

Question 9

Resistors

Answer 9

A component that provides resistance to control the current flowing through the circuit

Two types of resistors: Fixed & variable

Ohm’s Law :D

Question 10

Power

Answer 10

Rate of doing work or rate of energy conversion

Question 11

Heating Effect of Current

Answer 11

Heat is produced when current passes through a conductor. This is called the heating effect of current and it is caused by the conversion of electrical energy to heat.

Heating is undesirable -> Overheat -> Damaged

Question 12

Power rating

Answer 12

The maximum power at which a component or device can be used without being damaged.

Select a resistor that is capable of dissipating two ore more its computed power.

Question 13

Formula

Answer 13

I = Q/t
V = E/Q
V = IR
P = E/t
P = VI
P = I^2 R
P = V^2/R
E = Pt
E = VIt

Question 14

Efficiency

Answer 14

Useful energy OR power over total x 100%

Question 15

Energy

Answer 15

kWh is the unit used in utility bill