more conductor etc

Question 1

what are the features of a conductor (3)

Answer 1

• no energy gap
• highly conductive
• one or more bands are partially filled

Question 2

what are the features of an insulator (4)

Answer 2

• large energy gap
• valence band is full
• at room temperature there is not enough energy to move electrons from the valence band into the conduction band
• no electrical conduction

Question 3

what are the features of a semi-conductor (3)

Answer 3

• small energy gap
• at room temperature there is sufficient energy to move electrons from the valence band to the conduction band
• increase in temperature increases the conductivity of the semi-conductor

Question 4

what does forward bias do to a p-n junction

Answer 4

reduces the electric field

Question 5

how to decrease random uncertainties

Answer 5

• use a meter with smaller divisions

- take more readings of data

Question 6

what velocity can be worked out using the doppler equation (3)

Answer 6

• velocity of source
• velocity of light
• the radial velocity of a star moving directly towards or away from an observer

Question 7

how do u determine the temperature of a stellar object?

Answer 7

measure the peak wavelength of radiation emitted by the star

Question 8

define projectile motion

Answer 8

constant horizontal velocity and constant vertical acceleration

Question 9

what do crosses mean in a magnetic field

Answer 9

going into the page

Question 10

what do dots mean in a magnetic field

Answer 10

going out of the page

Question 11

how much light gets through a prism

Answer 11

100%

Question 12

how much light goes through a grating

Answer 12

not all / not 100%

Question 13

does red light diffract the least or the most

Answer 13

most

Question 14

does red light refract least or the most

Answer 14

least

Question 15

what does equation W=QV stand for

Answer 15

work done = charge x voltage

Question 16

why does a nuclear fission reaction release energy

Answer 16

there is a loss in mass which is converted into energy

Question 17

m x wavelength = ?

Answer 17

path difference

Question 18

why is AC current used in a particle accelerator

Answer 18

so that the particles remain accelerating in the same direction ( if DC was used the electron would be attracted back to the positive side)

Question 19

is the observed length longer or shorter than the actual length of an object

Answer 19

shorter because you multiply the length by a number less than 1!!!!

Question 20

hotter starts are —-1—- emitting more light at a —–2— wavelength, —-3—- frequency.

Answer 20

1 bluer 2 short 3 high