Technology in Space

Question 1

EMF - Electric Motor Force

Answer 1

the total energy that it (power supply) suppliers to each coulomb of charge - push of the cell

Question 2

Current

Answer 2

the rate of flow of charge

Question 3

Conservation of charge

Answer 3

charge is not created or destroyed it is conserved

Question 4

Potential difference

Answer 4

energy used by a coulomb to pass a component - energy per unit charge

Question 5

Adding resistors in parallel

Answer 5

reduces the total resistance of the circuit

Question 6

Series circuit

Answer 6

current the same, p.d shared

Question 7

Parallel circuit

Answer 7

p.d same, current shared

Question 8

Resistance –> Current

Answer 8

the more easily charge can flow, the lower its resistance and the greater the current will be for a given voltage

Question 9

What happens if you increase the resistance?

Answer 9

needs more energy to get through the components so p.d increases as cell gives some of its internal resistance to the circuit

Question 10

Lost volts

Answer 10

• internal resistance in the cell
• the energy needed to go through the cell
• you can never measure the true EMF with a voltmeter over a component due to this

Question 11

Power

Answer 11

the rate at which energy is transferred

Question 12

When will you get maximum power output?

Answer 12

when the load resistance equals the internal resistance however the efficiency will decrease and only 50% will be useful

Question 13

Negative temperature coefficient

Answer 13

as the temperature increases the resistance decreases - exponential ddecrease

Question 14

Positive temperature coefficient

Answer 14

as the temperature increases the resistance increases - linear

Question 15

Explain a PTC

Answer 15

resistance is collisions between electrons and positive lattice ions –> the temperature increases so the lattice ions vibrate more causing more collisions and therefore more resistance

Question 16

Explain a NTC

Answer 16

• usually semiconductors so no delocalised (free) electrons
• as the temperature increases they become better conductors as electrons become delocalised so the resistance decreases but as they become delocalised they begin to become a PTC

Question 17

Drift Velocity

Answer 17

some particles can move when a p.d is applied - negative particles move to positive terminal and vice versa forming a current

Question 18

Gold leaf experiment

Answer 18

• the rod is positive so when placed near the plate it will attract free electrons to the top
• this means the bottom will be positive and the top will be negative
• because the bottom and the gold leaf have the same charge they will repel each other raising the gold leaf

Question 19

Gold leaf: 1 photon is absorbed

Answer 19

by 1 electron (giving it enough energy to leave meaning the gold leaf falls as it is discharged)

Question 20

Gold leaf: What effect does ultra violet light have?

Answer 20

• it can cause the gold leaf to fall immediately if there’s a negative charge on the plate
• if the plate is positive or red laser light is used, these have no effect

Question 21

Gold leaf: How does the ultra violet light work?

Answer 21

gives the photoelectron energy when absorbed meaning the photoelectron has enough energy to leave –> this means ultraviolet light is not just a wave but a particle

Question 22

Ultraviolet light is a wavicle

Answer 22

-this means it is in between a wave and a particle –> sometimes it has wave properties and sometimes it has particle properties depending on the situation

Question 23

Work Function

Answer 23

the minimum amount of energy needed for the electron to leave the surface (changes from metal to metal)

Question 24

How does the intensity affect the photons released?

Answer 24

more photons are released