E.m.f And Internal Resistance

Question 0

Internal resistance makes what

Answer 0

BATTERIES and CELLS warm up

Question 1

What does resistance come from

Answer 1

ELECTRONS colliding with ATOMS and losing ENERGY

Question 2

Why does batteries warm up

Answer 2

Use CHEMICAL energy to make ELECTRONS move
As they move, they COLLIDE with atoms inside the BATTERY
So resistance must have resistance- this is called internal resistance

Question 3

How does the chemical energy make he electrons move

Answer 3

Chemical reactions in the battery produce electrical energy

Question 4

What is load resistance also known as

Answer 4

External resistance

Question 5

What is load/external resistance

Answer 5

The TOTAL RESISTANCE of ALL the COMPONENTS in the EXTERNAL circuit

Question 6

What is e.m.f

Answer 6

The AMOUNT of ELECTRICAL ENERGY
PRODUCED by the BATTERY
for each COULOMB of CHARGE
Isn’t actually a force-measures in volts

Question 7

What does e.m.f stand for

Answer 7

Electromotive force

Question 8

What is the potential difference across you load resistance

Answer 8

The ENERGY TRANSFERRED
when ONE COULOMB of CHRAGE
flows through the LOAD RESISTANCE

Question 9

If there is no internal resistance what should we notice about the terminal p.d and the e.m.f

Answer 9

Should be the same

Question 10

What is the potential difference across the load resistance called

Answer 10

Terminal p.d

Question 11

What is lost volts

Answer 11

The ENERGY WASTED
PER COULOMB
OVERCOMING
the INTERNAL RESISTANCE

Question 12

What does the conservation of energy tell us

Answer 12

Energy per coulomb SUPPLIED by the SOURCE = energy per coulomb USED in LOAD resistance + energy per coulomb WASTED in INTERNAL resistance

Question 13

What are the symbols of each:
Load/external resistance 
Terminal p.d
Internal resistance 
Electromotive force
Lost volts

Answer 13

R
V
r
e
v

Question 14

We are given this equation
V=e-Ir
What can we sub in to change it to make another one

Answer 14

V=IR

v=Ir

Question 15

What need low internal resistance

Answer 15

Powerful supplies

Question 16

Why does a car battery need to have a low internal resistance

Answer 16

As it has to DELIVER a really high CURRENT

Question 17

What are also the same

Answer 17

CELLS used to POWER a torch or a personal stereo

Question 18

Generally batteries have an internal resistance of what

Answer 18

Less than 1 ohm

Question 19

Since internal resistance caused energy loss, what would you think

Answer 19

All POWER SUPPLIES should have a LOW INTERNAL RESISTANCE

Question 20

What are the exception

Answer 20

HIGH VOLTAGE POWER SUPPLIES

Question 21

Name some high voltage power supplies which are designed with a very high internal resistance

Answer 21

HT (high tension)

EHT (extremely high tension)

Question 22

Why do high voltage power supplies have a very high internal resistance

Answer 22

If they are accidentally SHORT-CIRCUITED
only a VERY SMALL CURRENT can flow
-SAFER

Question 23

How would you use a circuit to measure internal resistance and e.m.f

Answer 23

Changing value of R (load resistance) measuring I and V
Plot graph of V against I
Use equation V=e-Ir rearrange to V=-rI+e
Gradient is -r     (V/I) 
Y intercept is e

Question 24

What is an easier way to measure the e.m.f of a power source

Answer 24

Connecting a HIGH-RESISTANCE VOLT ETER across its terminals
A SMALL CURRENT FLOWS through the VOLTMETER
So there must be some LOST VOLTS
Means you measure value SLIGHTLY LESS THAN the e.m.f