Electricity

Question 1

What is the rule with current and potential difference in a series circuit?

Answer 1

Current is the same everywhere
Potential difference is shared between components.

Question 2

What is the rule with current and potential difference in a parallel circuit?

Answer 2

Current is shared between loops
Potential difference is the same for each loop.

Question 3

What is current?

Answer 3

The rate of flow of charge.

Question 4

What is the equation for current?

Answer 4

Charge / time

Question 5

What is conventional current?

Answer 5

Current that flows from positive to negative ( sides of a battery )

Question 6

What is potential difference?

Answer 6

The work done per unit charge between 2 points in a circuit
(or energy transferred per coulomb)

Question 7

What is the equation for voltage?

Answer 7

Work done / charge

current x resistance

Question 8

How much resistance does an ammeter have?

Answer 8

None

Question 9

How much resistance does a voltmeter have?

Answer 9

Infinite

Question 10

What is resistance?

Answer 10

A measure of how difficult it is for charge carriers to pass through a component

Question 11

What is ohms law?

Answer 11

The law states that for an ohmic conductor, the current passing through it is directly proportional to the potential difference across it, providing that physical conditions, like temperature, remain constant.

Question 12

What is an ohmic conductor?

Answer 12

A component that follows ohms law

Question 13

What is a diode?

Answer 13

They are made from semiconductors and are designed to let current flow in one direction only

Question 14

What are the I-V characteristics of an ohmic conductor?

Answer 14

Directly proportional, straight line through the origin

Question 15

What are the I-V characteristics of a diode?

Answer 15

The forward bias is the direction in which the current is allowed to flow.
The direction of reverse bias, the resistance will be extremely high meaning only a small current can flow

Question 16

Explain in terms of electron motion, why the I-V characteristics for the filament lamp is a curve.

Answer 16

An increase in current leads to an increase in temperature, this causes an increase in the movement of the atoms in the metal wire, causing more frequent collisions with the electrons, causing resistance to increase shown by I/V changing.

Question 17

What is resistivity?

Answer 17

A measure of how easily a material conducts electricity, it is defined as the product of resistance and cross sectional area, divided by the length of the material

Question 18

What happens to the resistivity of a thermistor if temperature increases?

Answer 18

The resistance will decrease, as this causes electrons to be emitted from atoms, therefore the number of charge carriers increases and so the current increases, decreasing resistance, and therefore it’s resistivity

Question 19

What is Power?

Answer 19

The rate of energy transfer

Question 20

What is the electromotive force?

Answer 20

The energy transferred by a cell per coulomb of charge.

Question 21

What is internal resistance?

Answer 21

It is where electrons collide with atoms inside the battery, therefore some energy is lost before electrons even leave the battery.

Question 22

What are Kirchhoff’s laws?

Answer 22

1) The total current entering a junction = the total current leaving it.
2) The total voltage in a series circuit (sum of all components voltage) is equal to the voltage of the battery.

Question 23

What is a potential divider?

Answer 23

It is a circuit with several resistors connected in series across a voltage source used to produce a required fraction