static electricity (topic 2)

Question 1

(4)

Answer 1

• friction (between cloth and rod) causes
• electrons (to) move
• from the acetate rod to the cloth
• (net) charge on cloth is now negative
• (net) charge on rod is now positive

Question 2

Answer 2

• there is a force of attraction between the acetate rod and the cloth
• unlike charges attract

Question 3

Answer 3

• (bottom ends) move apart or repel
• have same charge (both have negative charge)
• same or like charges repel

Question 4

Answer 4

positive
electrons
cloth
strips

Question 5

Answer 5

• becomes (electrically) charged or
• comb attracts paper
• charge gone to Earth (body)

Question 6

Answer 6

• copper
• it is an (electrical) conductor

Question 7

Answer 7

• refuelling an aircraft
• a spark may cause an explosion / fire / ignite the fuel

Question 8

Answer 8

• (forces are) equal
• (forces act in) opposite directions

Question 9

(2)

Answer 9

• friction (between fleece and shirt)
• (causing) electrons to transfer from one to the other

Question 10

(2)

Answer 10

• transfer of electrons
• from cloth to the rod

Question 11

explain why when the negatively charged rod is placed near a thin stream of water, it causes the stream of water to deflect (2)

Answer 11

• the negatively charged electrons in the stream of water are repelled by the negatively charged electrons in the rod
• causing the water to experience a force deflecting it

Question 12

the student accidentally puts the negatively charged rod in the stream of water, explain why the stream of water does not deflect as far as before (3)

Answer 12

• the rod has lost some of it’s charge
• electrons have been transferred
• from the rod to the water

Question 13

one of the negatively charged balloons is now placed carefully on a vertical wall, explain why the balloon does not fall to the ground (3)

Answer 13

• the negative charge of the balloon repels the electrons in the surface of the wall
• electrons in the surface of the wall are repelled deeper into the wall, leaving the surface with a net positive charge
• the negative charge of the balloon is attracted to the positive charge in the surface of the wall

Question 14

as aircraft fly through the air, they become statically charged, explain how an aircraft could become charged during flight (2)

Answer 14

• as the aircraft flies through the air, it rubs against the air
• electrons are transferred leaving the aircraft electrically charged

Question 15

describe why it is dangerous to refuel a statically charged aircraft (2)

Answer 15

• the aircraft could cause a spark
• igniting the aviation fuel

Question 16

before aircraft are refuelled, they are connected to Earth by an electrical cable, explain why this makes refuelling safe (2)

Answer 16

• the earthing cable discharges any static charge that built up during the flight
• this prevents any sparks discharging from the aircraft, which could ignite the fue

Question 17

Answer 17

Question 18

(3)

Answer 18

• the negative charge of the comb repels the electrons in the paper
• electrons in the paper move further away from the surface, leaving a positive charge at the surface of the paper
• the positive charge at the surface of the paper is strongly attracted to the negative charge of the comb
• pieces of paper experience a force due to the attraction and jump up to stick to the comb

Question 19

the student rubs a metal rod with a cloth and brings it close to the pieces of paper, explain what happens to the pieces of paper (2)

Answer 19

Question 20

(3)

Answer 20

• the belt rubs against the comb
• causing electrons to be transferred
• from the dome to the belt

Question 21

before the teacher turned on the Van de Graaff generator, he placed a pile of metal cake cases on top, the cake cases also became positively charged, explain the cake cases need to be made from metal (2)

Answer 21

• metal is a good conductor of electricity
• this allows charge to build up on the cake cases

Question 22

the teacher turns on the Van de Graaff generator, explain why the metal cake cases begin to fly off after a short period

Answer 22

• (as the belt spins,) electrons are removed from the metal dome leaving the dome positively charged
• the metal cases are in contact with the metal dome and also become positively charged
• the cake cases repel each other and the Van de Graaff generator due to having the same charge
• the cases experience a force due to the electrostatic repulsion, causing them to fly off

Question 23

when the ball touches the negatively charged metal plate it becomes charged, explain why (2)

Answer 23

• electrons are transferred
• from the plate to the ball

Question 24

the ball now swings rapidly across towards the positively charged plate after touching the negatively charged metal plate, explain why (2)

Answer 24

• the ball and the metal plate both have a negative charge
• the negatively charged plate repels the ball across to the positively charged plate
• the positively charged plate attracts the negatively charged ball

Question 25

(1)

Answer 25

the ball oscillated between the plates 4 times per second

Question 26

Answer 26

Question 27

(3)

Answer 27

- as the paint leaves the spray gun it is negatively charged - the negatively charged paint droplets repel - spreading out to form a fine mist

Question 28

explain why is the car positively charged (2)

Answer 28

Question 29

(2)

Answer 29

- electrons are transferred - from the slide to the child

Question 30

explain why the childs hair is standing on end (3)

Answer 30

- each hair strand is negatively charged - like charges repel - hair feels repulsive force causing it to spread out

Question 31

the child gets off the slide and touches the metal frame of the slide, explain what happens to the negatively charged childs hair (2)

Answer 31