A point charge $q_1$ exerts a force $F$ on another point charge $q_2$ when placed at a fixed distance. If another point charge $q_3$ is brought near $q_2$, the force on $q_2$ due to $q_1$ :
a.
increases
b.
decreases
c.
may increase or decrease
d.
does not change
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Q2mcq1 mark
Equipotential surfaces for an isolated point charge are ________ in shape.
a.
spherical
b.
planar
c.
cylindrical
d.
conical
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Q3mcq1 mark
Resistivity of a metal wire depends on its :
a.
area of cross-section
b.
length
c.
material
d.
volume
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Q4mcq1 mark
The following table lists magnetic fields due to different current configurations. Column β I lists the current configurations and Column β II lists expressions for magnetic fields. Symbols have usual meanings.
Column β I | Column β II
---|---
i) At a distance r from an infinitely long straight wire. | p) $B = \mu_0 nI$
ii) At the centre of a circular current loop of radius r. | q) $B = \frac{\mu_0 I}{2r}$
iii) At the centre of a current carrying solenoid. | r) $B = \frac{\mu_0 I}{2\pi r}$
Match the current configurations in Column β I with the correct magnetic field expressions in Column β II.
a.
(i) β (p), (ii) β (q), (iii) β (r)
b.
(i) β (r), (ii) β (q), (iii) β (p)
c.
(i) β (r), (ii) β (p), (iii) β (q)
d.
(i) β (q), (ii) β (r), (iii) β (p)
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Q5mcq1 mark
βThe net magnetic flux through any closed surface is zeroβ. This law is called
a.
Gaussβ law in electrostatics
b.
Gaussβ law in magnetism
c.
Ampereβs circuital law
d.
Faradayβs law of electromagnetic induction
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Q6mcq1 mark
Consider the following statements :
Statement β 1 : A.C. Generator works on the principle of electromagnetic induction
Statement β 2 : In an A.C. Generator , as the armature is rotated in a uniform magnetic field , the magnetic flux linked with the coil changes which induces an emf in the coil.
Among the above two statements :
a.
Both Statements are true
b.
Both Statements are false
c.
Statement-1 is true and Statement-2 is false
d.
Statement-1 is false and Statement-2 is true
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Q7mcq
When a.c. is passed through an a.c. circuit, it is observed that the voltage and the current are in phase. Along with the a.c. source, the circuit :
a.
has a series combination of resistance and capacitance.
b.
has only inductance.
c.
has only capacitance.
d.
may have only resistance or may have a suitable series combination of inductance (L), capacitance (C) and resistance (R).
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Q7mcq1 mark
The variation of voltage and current through an a.c. circuit with time is as shown in the figure. Along with the a.c. source, the circuit :
a.
has a series combination of resistance and capacitance
b.
has only inductance
c.
has only capacitance
d.
may have only resistance or may have a suitable series combination of inductance (L), capacitance (C) and resistance (R)
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Q8mcq1 mark
Transformer cores are usually laminated. This is to reduce energy loss due to
a.
flux leakage
b.
winding resistance
c.
eddy currents
d.
hysteresis
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Q9mcq1 mark
βAmpere-Maxwell Lawβ is written as (symbols have usual meanings) :
Which one of the following statements is WRONG about interference of light?
a.
Light waves of same wavelength coming from two independent sources can be coherent and can produce interference
b.
When the path difference between two interfering waves is $n\lambda$, bright fringe is produced (Here $n = 0, 1, 2, ....$ and $\lambda$ is the wavelength of light)
c.
When the phase difference between two interfering waves is $(2n+1)\pi$, dark fringe is produced (Here $n = 0, 1, 2, ..)$
d.
In Youngβs double slit experiment, dark and bright fringes are equally spaced
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In Rutherfordβs Ξ±-ray scattering experiment, Ξ±-particles of specific energy are projected towards a thin gold foil. If the impact parameter for the Ξ±-particles is zero, the angle of scattering is
a.
$\theta = 0^\circ$
b.
$\theta = 90^\circ$
c.
$\theta = 180^\circ$
d.
$\theta = 45^\circ$
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Define electric potential energy of a system of charges. What happens to the potential energy of a system of two unlike charges when the distance between them is increased (assume there is no external electric field)?
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An intrinsic semi conductor crystal is doped with pentavalent atoms has an electron concentration of $10^{22} \times 5 \text{ m}^{-3}$. If, at thermal equilibrium, the intrinsic concentration $n_i = 1.5 \times 10^{16} \text{ m}^{-3}$, find the hole concentration.
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When a light radiation of energy 3 eV falls on a metal surface, photoelectrons with a maximum kinetic energy 1 eV are emitted from the surface. Find the threshold frequency for the metal surface. (Given: Planckβs constant, $h = 6.63 \times 10^{-34} \text{ Js}$; Charge on the electron $e = 1.6 \times 10^{-19} \text{ C}$).
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Obtain the expression for the force per unit length between two infinitely long straight parallel current carrying conductors placed in vacuum. Hence define the unit βampereβ.
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A uniformly charged spherical shell of radius 10 cm has a surface charge density of $16 \text{ } \mu\text{cm}^{-2}$. Find the electric field due to the shell at a distance of a) 20 cm from the centre of the shell, b) 5 cm from the centre of the shell.
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A uniformly charged spherical shell of radius $10\text{ cm}$ has a surface charge density of $16\ \mu\text{C m}^{-2}$. Find the electric field due to the shell at a distance of:
a) $20\text{ cm}$ from the centre of the shell.
b) $5\text{ cm}$ from the centre of the shell.
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Two identical cells each of emf 15 V either connected in series or connected in parallel across an external resistance of $5 \text{ } \Omega$ produce the same current through the resistor. a) Calculate the value of internal resistance of the cell. b) Find the current through the external resistor in either case.
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A series LCR circuit with $L = 0.5\text{ H}$ and $R = 100\ \Omega$ is connected to a $200\text{ V}, 50\text{ Hz}$ a.c. supply.
a) Calculate the value of capacitance of the capacitor that drives the circuit into resonance.
b) Find the value of voltage across the inductor at resonance.
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An object of height $1\text{ mm}$ is kept perpendicular to the axis of a thin convex lens of power $+10\text{ D}$. The distance between the object and the lens is $15\text{ cm}$. Find the position and height of the image formed.
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