[phy204]

1 The force per unit charge refers to ---------

electric potential

electric current

elctric field

electromotive force




2 An insulating material is said to be --------

paramagnetic

dieletric

superconducting

semiconducting




3 An electric field has a magnitude of 350N/C and makes an angle of 50o at each point on a flat rectangular horizontal surface of dimensions 20cm by 15cm. Calculate the electric flux for this surface

6 72Nm2 C

1 67Nm2 C

8 23Nm2 C

7 36Nm2 C




4 An electrical device in which two parallel conducting plates are in proximity but separated by an insulating material is called a ---------

inductor

resistor

capacitor

semiconductor




5 Two parallel conducting plates of area 100cm-squared in a vacuum are each given equal but opposite charges of 8 9 10−7C . What is the magnitude of the electric field between the plates? Take o=8 85 10−12C2 Nm2

107N C

206N C

303N C

404N C




6 A 2.0F capacitor is desired. What should be the area of the plates if they are to be separated by a 4.5mm air gap? Take o=8 85 10−12C2 Nm2

107m2

205m2

109m2

303m2




7 Capacitance of a capacitor depends on all of the following EXCEPT -------------

potential difference across the capacitor

area of the plates of the capacitor

distance of one plate from the other

electric current through the capacitor




8 Find the charge on a 1000 pF capacitor when charged to a voltage of 24V

0.24 C

0.048 C

0.024 C

0.48 C




9 Calculate the electric field between two plates which are 2cm apart in a vacuum and connected to a 120v battery

2400V/m

6000V/m

3000V/m

4000V/m




10 A 1.2 microfarad capacitor is charged to 3 kV. Calculate the energy stored in the capacitor

5.4J

3.3J

1.7J

12.8J




11 Two identical capacitors are connected in parallel, charged by a battery of voltage V, and then isolated from the battery. One of the capacitors is then filled with a material of relative permittivity K. What is the final potential difference across the plates of the capcitor

2KV

2V/K

2V/(K+1)

2V/(K-1)




12 Which of the following correctly represents the dimensions of dipole moment?

[charge]

[length]

[carge][length]

[charge]/[length]




13 A neutral molecule placed in an electric field becomes ------------

discharged

ionised

polarised

charged




14 A molecule in which the centre of the electron cloud does NOT coincide with the cenre of the nuleus is called ----------- molecule

dielectric

ferromagnetic

polar

diamagnetic




15 Which of the following statements is correct?

polar molecule has induced dipole moment

a non-polar molecule has permanent dipole moment

a non-polar molecule acquires a dipole moment in the presence of an electric field

a polar molecule acquires permanent dipole moment in the presence of an electric field




16 When a rectangular dielectric slab is placed in an electric field,

polarisation charges appear on the surfaces of the dielectric perpendicular to the field

surface charges appear on the surfaces of the dielectric parallel to the field

the induced dipole moment decreases with increase in the field

surface density of bound charges does not depend on the shape of the dielectric material



17 The correct dimensions of polarisation is ----------

[charge]/[length]

[charge][length]

[charge]/[length squared]

[charge]/[length cubed]




18 A dielectric material in which the magnitude and direction of the induced dipole momement do not depend on the orientation of the crystal axis with respect to the direction of the external electric field is called --------- dielectric

crystalline

amorphous

anisotropic

isotropic




19 A surface element of a dielectric material dS is inclined at an angle A to the direction of the external electric field. Given that the dipole moment per unit volume is P, then surface charge density aqcuired by the material is

PdSsinA

PdStanA

PdScotA

PdScosA




20 A device usually used for storing charges in electrical circuits is ---------------

inductor

capacitor

resistor

insulator