Physics (14-2-19)

Question 1

write the equation to calculate efficiency

Answer 1

useful energy transferred by the device/ total energy supplied

Question 2

state the six stores of energy

Answer 2

chemical 
kinetic 
thermal
elastic potential 
gravitational potential 
nuclear

Question 3

describe the particle movement of longitudinal waves

Answer 3

particles move back and forth (parallel) in the same direction as the wave is travelling

Question 4

state the 2 equations to calculate wave speed

Answer 4

wave speed = distance/ time
v = x / t

wave speed = frequency x wavelength
v = f x λ

Question 5

give one use for each of the 7 waves in the electromagnetic spectrum

Answer 5

radio waves - broadcasting, communications, satellite transmissions

microwaves - cooking, communications, satellite transmissions

Infrared radiation - cooking, thermal imaging, short range communications, optical fibres, TV remotes, security systems

visible light - vision, photography, illumination

Ultraviolet - security marking, fluorescent lamps, detecting forged bank notes, disinfecting water

X-rays - observing internal structure of objects, airport security, medical x-rays

Gamma - sterilising food and medical equipment, detection and treatment of cancer

Question 6

specify 5 waves of the EM spectrum and give a danger associated with them

Answer 6

microwaves - internal heating of body cell

infrared - skin burns

UV - damage to surface cells and eyes leading to skin cancer and eye conditions

X-rays and gamma rays - mutation or damage to cells in the body

Question 7

define power

Answer 7

rate at which energy is transferred

Question 8

how do you calculate work done when given force and distance

Answer 8

E = f x d

force x distance

Question 9

how do you calculate power when given work done and time

Answer 9

power = work done x time 
P = E/t

Question 10

how should you put an ammeter into a circuit and what does it measure

Answer 10

in series
current
amps

Question 11

how should you put a voltmeter into a circuit and what does it measure

Answer 11

in parallel
voltage/potential difference
volts

Question 12

state the equation which links charge, current and time

Answer 12

charge = current x time 
Q = I x t

Question 13

what happens to the resistance of a filament lamp after it is turned on and how does this affect current

Answer 13

resistance increases and current decreases

Question 14

what happens to the resistance of a LDR as light intensity increases? What effect does this have on current

Answer 14

resistance decreases and current increases

Question 15

state the three ways of calculating power

Answer 15

P = E/t
work done / time

P= I x V
current x voltage

P =I squared x R
current squared x resistance

Question 16

identify the difference between A.C and D.C

Answer 16

A.C - direction of current keeps changing

D.C - direction of current stays the same and flowing in one direction