energy transfers save my exams

Question 1

alternating current

Answer 1

current that is changes direction periodically, consciously

Question 2

parallel circuit

Answer 2

each lamp supplied with the same voltage

the current in each lamp can be different so the lights can be at different intensity

Question 3

switches will be on if

Answer 3

same switch is flowing

Question 4

what do switches allow

plus example

Answer 4

the same light to be controlled

top of the stairs and bottom of the stairs

Question 5

efficiency of something

Answer 5

only 20 % of total input energy is converted into useful energy while the rest is dissipated/ wasted

Question 6

power energy transferred time

Answer 6

power = energy transferred divided by time

Question 7

KE =

Answer 7

half mass times velocity squared

Question 8

force work done distance

Answer 8

force = work done divided by distance

Question 9

what is direct current

Answer 9

it is current that passes in one direction only

Question 10

describe energy transfers process in a reservoir

Answer 10

A hydroelectric dam converts the potential energy stored in a water reservoir behind a dam to kinetic energy. As the water flows down through the dam its kinetic energy is used to turn a turbine.

Question 11

hydroelectric power station

Answer 11

Flooding of valley by. Building big dam

Rain water is caught and allowed through turbines GPE - KE when it falls - create electrify

Question 12

how does evaporation cooling work

Answer 12

fastest particles escape first - so the average energy in the remaining kinetic stores decreases - the drop in average energy causes a drop in temp

Question 13

what is the unit of charge

Answer 13

C

Question 14

what happens when output power decreases

Answer 14

current decreases

Question 15

advantages of series circuit

Answer 15

fewer wires needed and lower valves of resistance

Question 16

disadvantage of series circuit

Answer 16

if one component fail they all fail and there is no independent control

Question 17

what type of energy is there in a generator

Answer 17

kinetic and electrical

Question 18

nuclear fission realises energy in what form

Answer 18

the energy realsed is in the form of KE of the neutrons and nuclei which are emitted in each fission

Question 19

how does nucleus fission lead to a chain reaction

Answer 19

nucleus splits releasing neutrons which hit different nuclei

Question 20

at first the temp of water increases and after a while, the temp reaches a steady value below the boiling point of water explain why the temp reaches a steady valuve?

Answer 20

there are energy loses

rate of energy loss = rate of energy supply at steady temp

Question 21

A suit case falls over

explain why it losses gpe when it falls

Answer 21

Gpe depends on height and the hight has decreased