PHY102

Category: PHY102

PHY102

1 / 50

The energy stored in a system of charges is known as electrostatic potential ---------------------------

2 / 50

Charges of ${+}2$ C and ${-2}$ C are situated at points P and Q respectively which are at a distance apart. A point X is mid-way between P and Q. Which of the following correctly describes the electric field and the electric potential at point X?

electric field is toward P, electric potential zero

electric field is toward P, electric potential is positive

electric field is toward Q, electric potential is negative

electric field is toward Q, electric potential is zero

3 / 50

1 volt is equal to ________

1 watt/C

1 J/s C

1 N/C

1 J/C

4 / 50

A conductor 2cm long carrying a current of 8A lies at right angles to a magnetic field of which the flux density is 1.0T. Calculate the force exerted on the conductor

0.45N

0.16N

0.20N

0.25N

5 / 50

Field lines are drawn such that the lines per unit cross-section area is proportional to ---------------------------field.

6 / 50

When a copper surface is illuminated by radiation of wavelength 2537 angstrome units the value of the stopping potential is found to be 0.24volts. Calculate the work function of copper.

4.48eV

3.26eV

2.67eV

7.46eV

7 / 50

Which of the following is not true of an electrostatic force?

it is weaker than the gravitational attraction between the charged particles.

it is mutually attractive or repulsive

it obeys an inverse square law

it acts along the line joining the point charges

8 / 50

An ammeter is suspected of giving inaccurate readings. In order to confirm the readings, the ammeter is connected to a silver votltameter in series and a steady current is passed for one hour. The ammeter reads 0.56A and 2.0124g of silver is deposited. What is the error is the ammeter reading?

1.1A

0.06A

6.0A

0.11A

9 / 50

A voltmeter connected across a 60Hz ac source reads 240V. Write down the expression of the instanteneous voltage as a function of time.

339.4sin377t

377cos339.4t

240sin339.4t

240cos339.4t

10 / 50

From Gauss’ law which of the following is NOT correct?

The outward flux of electric field through an enclosed surface is proportional to the electric charges enclosed

The electric flux through a Gaussian surface is a vector product of the electric field and a unit vector perpendicular to and outward from the surface

The total electric flux through a cylinder placed in an electric field with its axis parallel to the field is zero

The field at a point outside a spherically symmetric charge is the same as the electric field at the same point due to a point charge at its centre.

11 / 50

A tiny ball of mass 0.60 g is suspended from a rigid support with a piece of thread in a horizontal electric field of intensity 700 N/C. The ball is in equilibrium when the thread is inclined at an angle of 20_{o} to the vertical. What are the magnitude and sign of the charge on the ball? Take g = 9.8m/s^{2}

$4.2\times10^-{6}$ C

${-}4.1\times10^{-3}$C

${-}3.1\times10^{-6}C

$3.2\times10^{-6}$ C

12 / 50

The work function of a metal is 3.45eV. Calculate th maximum wavelength of a photon that can eject photo-electrons from the metal

$1.6\times10^{-6}$m

$2.4\times10^{-8}$m

$3.6\times10^{-7}$m

$3.4\times10^{-7}$m

13 / 50

The minimum energy required to liberate an electron from a metal surface is called ---------------------------.

14 / 50

A proton is accelerated through a potential difference of 100V and the enters a region in which it is moving perpendicular to a magnetic field of flux density 0.20 T. Find the radius of the circular path in which it will travel.

0.3 km

0.7 km

0.9 km

0.5 km

15 / 50

<p style="text-align:left">Six equal point charges Q = 10nC are located at 2,3, 4,5,6,7m. Find the potential at origin.

16 / 50

What is the self - inductance of an air-core solenoid, 1m long and 0.05m in diameter, if it has 1400 turns?

3.63mH

5.23mH

4.84mH

2.42mH

17 / 50

The study of static charges is called ---------------------------

18 / 50

Electric field is measured in Newton per ---------------------------.

19 / 50

Property of magnetic material in which --------------------------- attracts or repels.

20 / 50

An electron enters a uniform magnetic field 0.20 T at an angle of $30^{o}$ the field. Determine the pitch of the helical path assuming its speed is $3times10^{7}$ m/s

56.1 m

37.8 m

90.6 m

46.5 m

21 / 50

The magnitude and direction of the earth's field varies with position over the --------------------------- surface.

22 / 50

The magnitude of the forces between charged spheres was first investigated by Charles ---------------------------

23 / 50

A magnetic field does not exert a force on a _________

magnet

steel pin

stationary charge

moving charge

24 / 50

1eV is the energy acquired by an electron in falling freely through --------------------------- 1volt.

25 / 50

The resistivity of a semiconductor decreases rapidly with increasing ---------------------------.

26 / 50

A body that absorbs all radiations falling on it is known as ---------------------------.

27 / 50

The principle that electric forces add vectorially is known as the principle of ---------------------------

28 / 50

In the method of charging by friction, The algebraic sum of the individual charges that is the net charge is ---------------------------.

29 / 50

An ac circuit consists of a voltage source $v = 200sin120pi{t}$ and a $6mu$F capacitor in series. Calculate the current established in the circuit

2.13A

0.64A

0.32A

1.24A

30 / 50

The variation of the compass from the north-south direction is called the ---------------------------

31 / 50

A galvanometer of resistance $120Omega$ a full scale deflection with a current of 0.0005A. How would you convert it to an ammeter that reads a maximum current of 5A?

connect $200.12\Omega$ in series to it

connect $0.012\Omega$ in parallel to it

connect $20.10\Omega$ in series to it

connect $2000\Omega$ in parallel to it

32 / 50

The force between electric charges is known as ---------------------------

33 / 50

In the space surrounding a wire carrying a steady current, there exists ________

a magnetic field circling the wire

an oscillating magnetic field

no magnetic field

a magnetic field pointing radially outward

34 / 50

Kirchhof's junction rule is statement of conservation of -----------

energy

momentum

charge

mass

35 / 50

Two identical balls balls P and Q, each of mass 0.20 g, carry identical charges and are suspended by two threads of equal length. The balls position themselves at equilibrium such that the angle between the threads is 60_{o}.If the distance between the the balls is 0.5m, find the charge on each of them. Take g = 9.8 m/s^{2}

$2.3\times10^-{6}$C

$3.1\times10^{-5}$ C

$1.8\times10^-{7}C

$1.1\times10^{-3}$C

36 / 50

The term 'lost volts' refers to -----------

energy per coulomb dissipated in the external (load) resistance

energy per coulomb wasted to heat up the connecting wires

energy per coulomb dissipated in the internal resistance of the source of emf

terminal potential difference

37 / 50

Calculate the electric field at distance of 320 cm from an infinitely long wire carrying a charge per unit length 8.3 C/m.

$4.66\times10^{10}$ N/C

$6.22\times10^{10}$ N/C

$3.26\times10^{10}$ N/C

$8.85\times10^{10}$ N/C

38 / 50

In the cathode ray oscilloscope, when fast moving electrons strike the glass screen coated with zinc and sulphide they cause ---------------------------.

39 / 50

The force that is responsible for holding electrons to nuclei to form atoms is called the --------------------------- force

40 / 50

The electric flux is a --------------------------- quantity.

41 / 50

What are the dimensions of the constant k in Coulomb’s law of electrostatics?

$ML^{2}T{-4} T{-2}A{-1}$

$M^{-2}L^{3}T^{2}A^{-1}$

$ ML^{3}T^{-4}A^{-2}$

$ML^{2}T^{3}A^{-2}$

42 / 50

At the _______ a dipping compass needle is horizontal and at the magnetic poles it is vertical.

43 / 50

Three point charges $$2mu{C$}, ${-}4mu{C}$$, and $$6mu{C}$$ are held at the corners of an equilateral triangle with sides equal to 3 cm.What is the resultant force in newtons on the $$2mu{C}$$ charge?

${-}40\vec{i}+63.7\vec{j}$

${-}80\vec{i}+69.3\vec{j}$

$80\vec{i}-69.3\vec{j}$

$40\vec{i}-63.7\vec{j}$

44 / 50

An RLC circuit is used to tune a radio set to receive NOUN RADIO broadcasting at 105.9MHz in the FM band. The resistance and the inductance of the circuit of the radio set are $12Omega$ and 1.4$mu$H respectively. What capacitance should the circuit have?

2.11pF

1.33mF

1.51$\mu$F

1.64pF

45 / 50

The force applied to a conductor is 10N if the charge in the conductor is 5C, what is the electric field intensity?

46 / 50

The following are true about electric field lines except that they ______

are drawn such that the magnitude of the field is proportional to the number of lines crossing a unit area perpendicular to the lines

do not intersect one another

give the direction of motion of a unit positive test-charge under the action of the electrostatic force

are discontinuous and may terminate in a vacuum

47 / 50

The --------------------------- is the SI Unit of electric charge

48 / 50

An air-cored transformer is assumed to be 100% efficient. The ratio of the secondary turns to the primary turns is 1:20. A 240V ac supply is connected to the primary coil and a $6Omega$ load is connected to the secondary coil. what is the current in the primary coil?

2.0A

0.14A

0.10A

40.0A

49 / 50

When beta decay occurs --------------------------- changes into a proton and electron.

50 / 50

For how long must a steady current of 2A flow through a copper voltameter to deposit $10^{-3}$kg of copper? Z for coper is 0.000329g/C

42.1min

25.3min

22.6min

30.2min

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