[AS] Electricity

Question 1

Define current

Answer 1

The rate of flow of charge

Question 2

What is the equation of charge?

Answer 2

I = (dQ)/(dt)

Question 3

In what direction does current flow?

Answer 3

From + to -

Opposite from electron flow

Question 4

Which direction do electrons flow?

Answer 4

• to +

Opposite from current flow

Question 5

What is the unit of charge?

Answer 5

The coulomb

Question 6

How is a coulomb defined?

Answer 6

The amount of charge that passes in one second when the current is 1A

Question 7

How do you attach an ammeter in a circuit?

Answer 7

In series

Question 8

What is the elementary charge, e?

Answer 8

1.60 x 10^-19

Question 9

Define potential difference

Answer 9

Work done per unit charge

Work done by a coulomb of charge to pass between two points

Question 10

What is the equation for voltage with work done and charge?

Answer 10

V = W/Q

Question 11

What carries charge in liquids and gases?

Answer 11

Ions

Question 12

What is the equation for kinetic energy?

Answer 12

½mv^2

Question 13

Define mean drift velocity

Answer 13

Average velocity of the charge carriers

Question 14

What is an ohmic conductor?

Answer 14

Ohmic conductors have a constant Resistance

Question 15

What 3 things determine resistance?

Answer 15

Length, area and resistivity

Question 16

What resistivity do superconductors have?

Answer 16

Zero

Question 17

How do you make a metal a superconductor?

Answer 17

Cool them down

Question 18

Define power

Answer 18

Rate of transfer of energy

Question 19

Why do things have resistance?

Answer 19

Electrons collide with atoms and lose energy to other forms

Question 20

What is internal resistance?

Answer 20

Resistance inside batteries which causes their cells to heat up

Question 21

What is emf?

Answer 21

The amount of electrical energy the battery produces for each coulomb of charge

Question 22

What is external resistance?

Answer 22

The total resistance of all components in the external circuit

Question 23

What is terminal p.d?

Answer 23

The energy transferred when one coulomb of charge flows through the external resistance

Question 24

What are the equations for emf that to use not given in the formula book?

Answer 24

Emf = V + v

V = (emf) - Ir

Question 25

How do you work out the emf of multiple cells on series? (e = emf because there is no symbol)

Answer 25

Emf = e1 + e2 + e3 ……

Question 26

How do you work out the emf of multiple cells on parallel? (e = emf because there is no symbol)

Answer 26

e = e1 = e2 = e3 = …….

Question 27

In a series circuit, if there is no internal resistance what happens is current and e.m.f??

Answer 27

Current is the same at all points on the circuit

E.m.f. Is split between components

Question 28

In a parallel circuit, if there is no internal resistance, what happens to current and p.d.?

Answer 28

Current is split at each junction

P.d across all components is the same

Question 29

Unless told otherwise, what is the resistance of ammeters and voltmeters??

Answer 29

Ammeters = zero 
Voltmeters = infinite

Question 30

How does length effect the current flow of a wire?

Answer 30

The longer the more difficult to make current flow

Question 31

How does area effect the current flow in a wire??

Answer 31

The wider the easier