Exam Questions

Question 1

which one of the following has different units to the other 3
A-gravitional potential
B-graviationl field strength
C- force per unit mass
D- gradational potenial gradient

Answer 1

answer = A

A = J/Kg

B/C/D = N/Kg

Question 2

which one of the following could be a unit of gravitational potential?
A- N
B- J
C- N/Kg
D- J/Kg

Answer 2

D

Question 3

define the gradational potential at a point in a gravitational field

Answer 3

work done per unit mass in moving a mass from infinity to a point

Question 4

state two situations in which a charged particle will experience no magnetic force when placed in a magnetic field

Answer 4

in line with a magnetic field

not moving

Question 5

a charged particle moves in a circular path when travelling perpendicular to a uniform magnetic field. by considering the force acting on the charged particle, show that the radius of the path is proportional to the momentum of the particles

Answer 5

F = mv^2/r
F=BQV

BQ are constant
R ∝ mv

Question 6

the speed of the protons gradually increases as their energy is increased by the LHC. state and explain how the magnetic field in the LHC must change as the speed of the protons is increased

Answer 6

r=mv/BQ
strength of magnetic field would increase
when B increases magnetic force must be increased to increase the centripetal force
keep r constant

Question 7

explain why the ions have no overall deflection when a magnetic field of the required strength has been applied

Answer 7

electric and magnetic field cancels each of the forces

forces are in opposite directions

Question 8

explain what would happen if the ions had a higher velocity when they pass between the plates at a time

Answer 8

path of ions would bend upwards

magnetic force increase but elecstatic force is uncharged

Question 9

an alternating current is passed through the wire. explain why the wire would vibrate vertically

Answer 9

force is perpendicular to both B and I.
magnitude of F changes as the size of current changes
force acts in opposite direction when the current is reserved
continuous reserves of ac current

Question 10

why does an meter briefly show a non-zero reading

Answer 10

magnetic flux linkage in the coil increase then becomes constant

Question 11

the output electromotive force (emf) of a simple ac generator can be increased
what factors should not be charged if the frequency of the output is to remain unaffected when the emf is increased
A- area of the coil
B-number of turns on the coil
C-speed of rotation
D-strength of the magnetic field

Answer 11

C

speed of rotation

Question 12

which one of the following statements is correct? an electron follows a circular path when it is moving a right angle to ..
A- uniform magnetic field
B- uniform electric field
C-unifrom electric and magnetic field which are perpendicular
D-unifrom electric and magnetic field which are in opposite directions

Answer 12

A- uniform magnetic field

Question 13

an electron moves due north in a horizontal plate with inform speed. it enters a uniform magnetic field directed due south in the same plane. which one of the following statements concerning the motion of the electron in magnetic field is correct?
A-accelerated due west
B-slows down to zero speed and accelerates due south
C- continuous to move north with its original speed
D-accelerated due north

Answer 13

C- continuous to move north with its original speed

Question 14

state the effect on the path if the strength of the magnetic field is doubled

Answer 14

r decrease (halve)

Question 15

when a charge moves between two points in an electric field, or mass moves between two points in a gravitational field, energy may be transferred
which one is correct?
A-no energy is transferred when the movement is parallel to the direction of the field
B-the energy transferred is independent of the start and finish points
C-energy transferred is independent of the path followed
D- energy transferred when the movement is perpendicular to the field lines

Answer 15

c

Energy transferred is independent of the path followed

Question 16

State in word coulombs law

Answer 16

force between two points is proportion; to product of charges and inversely proportional tot he square of their distance apart

Question 17

as the comet orbits the sun the distance between the comet and the sun continually changes. as the comet moves towards the sun this distance reaches a minimum value. which one these statement is incorrect
A-potential energy of the comet increase
B-gravational force acting on the comet increases
C-direction of the gradational force acting on the comet changes
D-kinetic energy of the comet increase

Answer 17

A-potential energy of the comet increase

Question 18

two satellites P and Q of the same mass are in circular orbits around the earth. the radius of the orbit of Q is three times of that P. watch statement is correct?
A-kinetic energy of P is greater than that of Q
B-weight of P is three times that of Q
C- time period of P is greater than that of Q
D- speed of P is three times that of Q

Answer 18

A-kinetic energy of P is greater than that of Q

Question 19

two satellites P and Q of equal mass orbit the earth at radii R and 2R. which one of the following is correct?
A- P has less kinetic energy and more potential energy than Q
B- P has less kinetic energy and less potential energy than Q
C - P has more kinetic energy and less potential energy than Q
D-P has more kinetic energy and more potential energy than Q

Answer 19

C - P has more kinetic energy and less potential energy than Q

Question 20

define electric field strength E at a point in the electric field

Answer 20

force per unit charge

acting on a positive charge

Question 21

define the electric potential at a point in an electric field

Answer 21

work doen per unit change of a positive test charge from infinity to a point