1: If L,C & R represent inductance, capacitance and resistance; then which of the following represents frequency?
a. L/R
b. 1/RC
c. 1 / $\sqrt{LC}$
d. All of these
2: A wire loop of radius r confined in a plane is rotated in its plane with some angular frequency ω A uniform magnetic field exists in region, the emf induced is
a. $\omega r^2B$
b. $\omega r^2B/2$
c. $2 \omega r^2B$
d. Zero
3: A magnet drops down a long vertical copper tube. Its velocity as it falls down the tube
a. Decreases
b. Increases
c. Remains constant
d. None
4: Two identical coils are mutually perpendicular such that their centres coincide. The ratio of magnetic field due to one coil to resultant of two coils is
a. 1:1
b. $1:\sqrt2$
c. $1:2$
d. None of these
5: A current in a coil of inductance 5H decreases at rate 2A/S The inductance emf is
a. 5V
b. 10V
c. -10V
d. None of above
6: A coil of copper wire is pulled in a magnetic field with constant velocity. If its resistance is increased then it is
a. Difficult to pull it
b. Easier to pull it
c. Impossible to pull it
d. None of above
7: Faraday’s laws are consequences of conservation of
a. Charge
b. Magnetic field
b. Impulse
d. Energy
8: An electron enters in a region where magnetic field, electric field and electrons are perpendicular to one another they will always move
a. In direction of magnetic field
b. In direction of electric field
c. In circle
d. None of these
9: If number of turns per unit length of a solenoid is doubled, inductance of solenoid will
a. Be constant
b. Be-halved
c. Become four times
d. Be-doubled
10: Which of the following is a scalar quantity?
a. Magnetic flux
b. emf ∊
c. Both a & b
d. None of these
11: A current loop placed in a magnetic field behaves like a
a. Magnetic
b. Magnetic pole
c. Magnetic dipole
d. All of these
12: The north pole of a long horizontal bar magnet is being brought closer to a vertical conducting plane along perpendicular direction. The direction of induced current in conducting plane will be
a. Vertical
b. Counter clock wise
c. Horizontal
d. All of these
14: The self-inductance of a straight conductor is
a. Zero
b. Infinity
c. Very small
d. None of these
15: If $V=\ V_Psin⍵t+60^o$ when will the voltage be maximum for first time?
a.
b. T/8
c. T/12
d. None of these
16: If power factor is 0.5 in a series RLC circuit with R=100Ω AC main is used when L is
a. $\sqrt3\pi H$
b. $(\sqrt3/\pi)H$
c. $(\pi/\sqrt3)$
d. None of these
17: In the transformer shown in fig 7.12, turns ratio is 3:1, then $V_0=$
a. 15V
b. 30V
c. Zero
d. None of these
18: In an oscillating LC circuit, maximum charge on capacitor is q. The on capacitor when energy is stored equally between electric and magnetic field is
a. $q/\sqrt2$
b. $q/\sqrt3$
c. q
d. q/2
19: A transformer has turns ratio $\frac{N_S}{N_P}=10\$ and load current is 1A. The current in primary coil is
a. 10A
b. 0.1A
c. 11A
d. None of above
20: If an iron rod is introduced in the inductor of circuit, then bulb
a. Gets brighter
b. Gets dimmer
c. Remains same
d. None of these
21: The dimensions of matches with
a. R/L
b. LR
c. L/R
d. None of these
22: The dielectric strength of air is .A parallel plate capacitor has area 20cm2 and plate separation is 0.1mm. The maximum voltage of an AC source which can be converted is
a. 426V
b. 300V
c. 210V
d. None of all
23: An AC source rated supplies a current 8A (r m s) to the circuit. The average power delivered by source is
a. 800W
b. >800W
c. <800W
d. $\le800W$
24: Two identical cells are first connected in series and then in parallel. The ratio of balancing lengths in two cases will be
a. 4:1
b. 1:4
c. 2:1
d. 9:1
25: Dimensions of $1/\sqrt{\mu_0\epsilon_0}$ are those of
a. Velocity
b. Momentum
c. Energy
d. None of these
26: A plane electromagnetic wave is $E=600\sin{\left({10}^6\pi t-kx\right)}$. The maximum magnetic field strength is
a. $4\times{10}^5T$
b. $2\times{10}^6T$
c. $2\times{10}^{-6}T$
d. None of these
27: A moving charge will produce
a. Electric field only
b. Magnetic field only
c. Both a & b
d. None of these
28: For electromagnetic waves, Maxwell generalized
a. Gauss’s law of electricity
b. Gauss’s law of magnetism
c. Ampere’s law
d. Faraday’s law
29: Which one of the following Maxwell equations says that isolated magnetic poles do not exist?
a. $div\vec{D}=\rho$
b. $\mathbf{div\vec{B}=0}$
c. Both a & b
d. Generalized Ampere’s law
30: Electromagnetic waves transport energy equal to
a. $mv^2/2$
b. $m_0c^2$
c. $\mathbf{hf}$
d. $hf/c$
31: Consider the radiation emitted by a human body. Which of the following is true
a. Lies in infrared region
b. Lies in UV region
c. Emitted during day only
d. Emitted during night only.
32: An electromagnetic wave goes from air to glass. Which of the following is not change
a. Wavelength
b. Amplitude
c. Frequency
d. Speed
33: Maxwell electromagnetic equations are valid under all conditions except one and that is
a. These do not apply to non-homogeneous media
b. These do not apply to non-isotropic media
c. These do not apply to non-linear media
d. All of these
34: The quantity $\sqrt{\frac{\mu}{\epsilon}} h$ has dimensions of
a. Electric field
b. Magnetic field
c. Inductance
d. Impedance
