A dipole is placed in an electric field as shown. In which direction will it move?
a.
towards the right as its potential energy will decrease.
Correct Answer
b.
towards the left as its potential energy will decrease.
c.
towards the right as its potential energy will increase.
d.
towards the left as its potential energy will increase.
Step-by-Step AI Explanation
Verified Method
A dipole in a non-uniform electric field experiences a net force. It moves towards the region of higher field intensity, which corresponds to a decrease in potential energy (U = -p.E).
Q2mcq
Consider the following statements (A) and (B) and identify the correct answer.
(A) A zener diode is connected in reverse bias, when used as a voltage regulator.
(B) The potential barrier of p-n junction lies between 0.1 V to 0.3 V.
a.
(A) and (B) both are incorrect.
b.
(A) is correct and (B) is incorrect.
Correct Answer
c.
(A) is incorrect but (B) is correct.
d.
(A) and (B) both are correct.
Step-by-Step AI Explanation
Verified Method
Zener diodes are indeed operated in reverse breakdown region to regulate voltage. For a Silicon p-n junction, the barrier potential is ~0.7 V, and for Germanium it is ~0.3 V. The range provided in statement (B) is too low for standard silicon junctions.
Q2mcq
Consider the following statements (A) and (B) and identify the correct answer.
(A) A zener diode is connected in reverse bias, when used as a voltage regulator.
(B) The potential barrier of p-n junction lies between 0.1 V to 0.3 V.
a.
(A) and (B) both are incorrect.
b.
(A) is correct and (B) is incorrect.
Correct Answer
c.
(A) is incorrect but (B) is correct.
d.
(A) and (B) both are correct.
Step-by-Step AI Explanation
Verified Method
Statement (A) is correct as Zener diodes operate in the reverse breakdown region. Statement (B) is incorrect because the potential barrier for Silicon is ~0.7V and for Germanium is ~0.3V; the range 0.1-0.3 is too narrow to be generally true for p-n junctions.
Q3mcq
In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?
In a potentiometer circuit a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?
a.
21.6 cm
b.
64 cm
c.
62 cm
d.
60 cm
Correct Answer
Step-by-Step AI Explanation
Verified Method
In a potentiometer, EMF (E) is directly proportional to balance length (l). So, E1/E2 = l1/l2. Therefore, 1.5/2.5 = 36/l2. Solving for l2: l2 = (36 * 2.5) / 1.5 = 36 * (5/3) = 12 * 5 = 60 cm.
Q4mcq
Match Column - I and Column - II and choose the correct match from the given choices.
(A) Root mean square speed of gas molecules (P) sqrt(3kT/m)
(B) Pressure exerted by ideal gas (Q) sqrt(3RT/M)
(C) Average kinetic energy of a molecule (R) (1/3)nmv^2
(D) Total internal energy of 1 mole of a diatomic gas (S) (5/2)RT
(A) is Q (sqrt(3RT/M)), (B) is P (1/3 nm v^2), (C) is S (3/2 kT), (D) is R (5/2 RT). Matching yields A-Q, B-P, C-S, D-R.
Q5mcq
The velocity of a small ball of mass M and density d, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is d/2, then the viscous force acting on the ball will be:
a.
Mg
b.
3/2 Mg
c.
2 Mg
d.
Mg/2
Correct Answer
Step-by-Step AI Explanation
Verified Method
At terminal velocity, buoyant force + viscous force = weight. Viscous force = Weight - Buoyant force. Buoyant force = (V * rho_liquid * g). Since M = V * d, V = M/d. Buoyant force = (M/d) * (d/2) * g = Mg/2. Viscous force = Mg - Mg/2 = Mg/2.
Q6mcq
An infinitely long straight conductor carries a current of 5 A as shown. An electron is moving with a speed of 10^5 m/s parallel to the conductor. The perpendicular distance between the electron and the conductor is 20 cm at an instant. Calculate the magnitude of the force experienced by the electron at that instant.
a.
8π * 10^-20 N
b.
4π * 10^-20 N
c.
8 * 10^-20 N
d.
4 * 10^-20 N
Correct Answer
Step-by-Step AI Explanation
Verified Method
B = mu_0 * I / (2 * pi * r) = (4 * pi * 10^-7 * 5) / (2 * pi * 0.2) = 5 * 10^-6 T. Force F = qvB = (1.6 * 10^-19) * (10^5) * (5 * 10^-6) = 8 * 10^-20 N. Re-checking math: B = 5e-6. F = 1.6e-19 * 1e5 * 5e-6 = 8e-20. Wait, calculation 1.6 * 5 = 8. Let's re-verify: F = q * v * (mu0 * I / (2 * pi * r)). F = 1.6e-19 * 1e5 * (2e-7 * 5 / 0.2) = 1.6e-19 * 1e5 * 5e-6 = 8e-20.
Q7mcq
Polar molecules are the molecules:
a.
acquire a dipole moment only in the presence of electric field due to displacement of charges.
b.
acquire a dipole moment only when magnetic field is absent.
c.
having a permanent electric dipole moment.
Correct Answer
d.
having zero dipole moment.
Step-by-Step AI Explanation
Verified Method
Polar molecules are those in which the centers of positive and negative charges do not coincide, resulting in a permanent electric dipole moment.
Q8mcq
A capacitor of capacitance 'C', is connected across an ac source of voltage V, given by V = V_0 sin(omega*t). The displacement current between the plates of the capacitor, would then be given by:
A cup of coffee cools from 90°C to 80°C in t minutes, when the room temperature is 20°C. The time taken by a similar cup of coffee to cool from 80°C to 60°C at a room temperature same at 20°C is:
a.
13t/5
b.
10t/13
c.
5t/13
d.
13t/10
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A nucleus with mass number 240 breaks into two fragments each of mass number 120, the binding energy per nucleon of unfragmented nuclei is 7.6 MeV while that of fragments is 8.5 MeV. The total gain in the Binding Energy in the process is:
a.
9.4 MeV
b.
804 MeV
c.
216 MeV
d.
0.9 MeV
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A radioactive nucleus X decays in the sequence X -> B -> C -> D, where Z is the atomic number of element X. The possible decay particles in the sequence are:
a.
α, β+, β-
b.
β+, α, β-
c.
β-, α, β+
d.
α, β-, β+
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The electron concentration in an n-type semiconductor is the same as hole concentration in a p-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them.
a.
current in p-type > current in n-type.
b.
current in n-type > current in p-type.
c.
No current will flow in p-type, current will only flow in n-type.
d.
current in n-type = current in p-type.
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A screw gauge gives the following readings when used to measure the diameter of a wire. Main scale reading : 0 mm. Circular scale reading : 52 divisions. Given that 1 mm on main scale corresponds to 100 divisions on the circular scale. The diameter of the wire from the above data is :
a.
0.026 cm
b.
0.26 cm
c.
0.052 cm
d.
0.52 cm
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The number of photons per second on an average emitted by the source of monochromatic light of wavelength 600 nm, when it delivers the power of 3.3×10^-3 watt will be : (h=6.6×10^-34 Js)
a.
10^17
b.
10^16
c.
10^15
d.
10^18
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A parallel plate capacitor has a uniform electric field ‘E’ in the space between the plates. If the distance between the plates is ‘d’ and the area of each plate is ‘A’, the energy stored in the capacitor is : (ε0=permittivity of free space)
a.
ε0EAd
b.
1/2 * ε0 * E^2 * Ad
c.
E^2 * Ad / ε0
d.
1/2 * ε0 * E
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A small block slides down on a smooth inclined plane, starting from rest at time t=0. Let Sn be the distance travelled by the block in the interval t=n-1 to t=n. Then, the ratio Sn / Sn+1 is :
a.
(2n-1)/(2n+1)
b.
(2n+1)/(2n-1)
c.
2n / (2n-1)
d.
(2n-1) / 2n
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Column-I gives certain physical terms associated with flow of current through a metallic conductor. Column-II gives some mathematical relations involving electrical quantities. Match Column-I and Column-II with appropriate relations.
Column-I: (A) Drift Velocity, (B) Electrical Resistivity, (C) Relaxation Period, (D) Current Density
Column-II: (P) m/(ne^2ρ), (Q) nev_d, (R) eEτ/m, (S) E/J
a.
(A)-(R), (B)-(S), (C)-(Q), (D)-(P)
b.
(A)-(R), (B)-(P), (C)-(S), (D)-(Q)
c.
(A)-(R), (B)-(Q), (C)-(S), (D)-(P)
d.
(A)-(R), (B)-(S), (C)-(P), (D)-(Q)
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The escape velocity from the Earth’s surface is v. The escape velocity from the surface of another planet having a radius, four times that of Earth and same mass density is :
a.
2v
b.
3v
c.
4v
d.
v
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The escape velocity from the Earth's surface is v. The escape velocity from the surface of another planet having a radius four times that of Earth and same mass density is:
a.
2v
b.
3v
c.
4v
d.
v
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The effective resistance of a parallel connection that consists of four wires of equal length, equal area of cross-section and same material is 0.25 Ω. What will be the effective resistance if they are connected in series?
a.
0.5 Ω
b.
1 Ω
c.
4 Ω
d.
0.25 Ω
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Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g=10 m/s^2)
a.
8.1 kW
b.
12.3 kW
c.
7.0 kW
d.
10.2 kW
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A step down transformer connected to an ac mains supply of 220 V is made to operate at 11 V, 44 W lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?
a.
0.4 A
b.
2 A
c.
4 A
d.
0.2 A
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A ball of mass 0.15 kg is dropped from a height 10 m, strikes the ground and rebounds to the same height. The magnitude of impulse imparted to the ball is (g=10 m/s^2) nearly :
a.
4.2 kg m/s
b.
2.1 kg m/s
c.
1.4 kg m/s
d.
0 kg m/s
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A ball of mass 0.15 kg is dropped from a height 10 m, strikes the ground and rebounds to the same height. The magnitude of impulse imparted to the ball is (g=10 m/s^2) nearly:
a.
4.2 kg m/s
b.
2.1 kg m/s
c.
1.4 kg m/s
d.
0 kg m/s
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Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 >> R2, the mutual inductance M between them will be directly proportional to:
a.
R1/R2
b.
R1^2/R2
c.
R2^2/R1
d.
R1/R2^2
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Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 >> R2, the mutual inductance M between them will be directly proportional to :
a.
R1 / R2
b.
R1^2 / R2
c.
R2^2 / R1
d.
R1 / R2^2
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A series LCR circuit containing 5.0 H inductor, 80 µF capacitor and 40 Ω resistor is connected to 230 V variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the power at the resonant angular frequency are likely to be :
a.
50 rad/s and 25 rad/s
b.
46 rad/s and 54 rad/s
c.
42 rad/s and 58 rad/s
d.
25 rad/s and 75 rad/s
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A car starts from rest and accelerates at 5 m/s^2. At t=4 s, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at t=6 s ? (Take g=10 m/s^2)
a.
20 m/s, 0
b.
20 sqrt(2) m/s, 0
c.
20 sqrt(2) m/s, 10 m/s^2
d.
20 m/s, 5 m/s^2
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A particular station of All India Radio, New Delhi, broadcasts on a frequency of 1,368 kHz (kilohertz). The wavelength of the electromagnetic radiation emitted by the transmitter is : [speed of light, c=3.0×10^8 ms^-1]
a.
219.2 m
b.
2192 m
c.
21.92 cm
d.
219.3 m
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Choose the correct option for the total pressure (in atm.) in a mixture of 4 g O2 and 2 g H2 confined in a total volume of one litre at 0°C. [R=0.082 L atm mol^-1 K^-1, T=273 K]
a.
2.602
b.
25.18
c.
26.02
d.
2.518
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