13.3- ELECTROMOTIVE FORCE AND INTERNAL RESISTANCE

Question 1

What is the internal resistance of a source of electricity due to?

Answer 1

opposition to flow of charger through source

Question 2

What does the opposition to flow of charge through source cause? (internal resistance)

Answer 2

causes electrical energy produced by source to be dissipated inside source when charge flows through it

Question 3

What is the electromotive force of a source?

Answer 3

electrical energy per unit charge produced by source

Question 4

What is the equation for electromotive force using charge?

Answer 4

ℰ= E/Q

Question 5

What is the p.d. across the terminals of a source?

Answer 5

electrical energy per unit charger delivered by source when it’s in circuit

Question 6

What is the terminal p.d. like in comparison to the emf whenever current passes through the source?

Answer 6

terminal p.d. less than emf

Question 7

What is the difference between the terminal p.d. and emf whenever current passes through the source due to?

Answer 7

internal resistance of source

Question 8

Defintion of internal resistance of source?

Answer 8

loss of potential difference per unit current in source when current passes through source

Question 9

Equation for emf with current?

Answer 9

ℰ = IR + Ir

Question 10

What is the lost pd inside the cell equal to?

Answer 10

difference between cell emf + pd across its terminals

Question 11

In energy terms, what is the lost pd?

Answer 11

energy per coulomb dissipated or wasted inside cell due to its internal resistance

Question 12

Equation for power supplied to cell using internal resistance?

Answer 12

Iℰ = I²R + I²r

Question 13

When is the maximum power delivered to load?

Answer 13

when load resistance equal to internal resistance of source

Question 14

How can the p.d. across the terminals of a cell, when the cell is in a circuit be measured?

Answer 14

by connecting a high-resistance voltmeter directly across terminals of cell

Question 15

When the pd across the terminals of a cell is measured, how is the current changed?

Answer 15

by adjusting the variable resistor

Question 16

When measuring the p.d. across the terminals of a cell, what does the lamp limit?

Answer 16

limits the maximum current that can pass through the cell

Question 17

How does the terminal p.d. change in relation to the current?

Answer 17

terminal p.d. decreases as the current increases

Question 18

Why does the terminal p.d. decrease as the current increases?

Answer 18

as the lost p.d. increases as the current increases

Question 19

What is the terminal p.d. equal to at zero current?

Answer 19

cell emf

Question 20

Why is the terminal p.d. equal to cell emf when the current is zero?

Answer 20

as lost p.d. zero at zero current

Question 21

Equation for terminal p.d.

Answer 21

V = ℰ - Ir

Question 22

What are the values of V = ℰ - Ir in relation to y = mx + c?

Answer 22

V- y-axis
I- x-axis
gradient- -r
y-intercept- ℰ