CBSE Class 11 Physics MCQs Set 5

Question. Intermolecular forces are attractive when the separation of molecules is...
[A] more than the equilibrium separation
[B] less than the equilibrium separation
[C] equal to the equilibrium separation
[D] zero
Answer: A

Question. The inter atomic potential is dependent on...
[A] the shape of the atoms only
[B] the distance between the atoms only
[C] both the shape and the distance between the atoms
[D] none of above
Answer: B

Question. The shear stress that acts on an object affects its...
[A] length
[B] width
[C] volume
[D] shape
Answer: D

Question. The only elastic modulus that applies to liquids is...
[A] Young's modulus
[B] Shear modulus
[C] modulus of rigidity
[D] bulk modulus
Answer: D

Question. In the steady flow, the streamlines...
[A] do not exist
[B] are fixed in number
[C] intersect one another
[D] do not intersect one another
Answer: D

Question. If the radius of a pipe is increased by 50%, the fluid velocity v becomes...
[A] (3/2).v
[B] (2/3).v
[C] (4/9).v
[D] (9/4).v
Answer: D

Question. The average speed of the molecules in a bottle of gas at pressure P and absolute temperature T is doubled. The new pressure and temperature are, respectively...
[A] 2P, 2T
[B] 4P, 4T
[C] 4P, 2T
[D] 2P, 4T
Answer: C

Question. In the equation, PV = constant, the value of the constant depends on...
[A] the temperature of the gas
[B] the mass of the gas
[C] the temperature and the mass of the gas
[D] the temperature and the pressure of the gas
Answer: B

Question. For water, triple point occurs at...
[A] 76 mmHg, 273.16K
[B] 76 mmHg, 273.16°C
[C] 4.58 mmHg, 273.16K
[D] 4.58 mmHg, 273.16°C
Answer: C

Question. The density of water is maximum at...
[A] 0°C
[B] 4°C
[C] 30°C
[D] 32°F
Answer: C

Question. Dipole moment is...
[A] a scalar
[B] a vector from -q to +q
[C] a vector from +q to -q
[D] a vector perpendicular to the distance vector
Answer: B

Question. If an ebonite rod is rubbed with fur...
[A] the rod gets electrified
[B] the fur gets electrified
[C] both the fur and the rod get electrified
[D] none gets electrified
Answer: B

Question. For a magnet placed in a magnetic field, the maximum torque occurs when the axis of the magnet is...
[A] perpendicular to the field
[B] parallel to the field
[C] inclined at 45° to the field
[D] inclined at 180° to the field
Answer: C

Question. Optical fibres use the principle of...
[A] refraction
[B] total internal refraction
[C] total internal reflection
[D] total internal absorption
Answer: A

Question. When light travels in different materials...
[A] the wavelength remains constant
[B] the frequency remains constant
[C] the velocity remains constant
[D] none of three remains constant
Answer: C

Question. If a star A is two magnitudes brighter than star B, we say that A is _____ times brighter than B.
[A] 2
[B] 2 x 2.512
[C] 2.512 x 2.512
[D] 100
Answer: B

Question. If λ is emitted wavelength, λ is measured wavelength and Z is the displacement of spectral line, then...
[A] Z = (λ - λ)/λ
[B] Z = (λ - λ)/λ 
[C] λ = λ (Z + 1)
[D] λ = λ(Z + 1)
Answer: C

Question. The magnitude of vector 2i - 3j + √ 3.k is...
[A] 2
[B] 3
[C] √ 2
[D] 4
Answer: C

Question. The M.I. of a disc about an axis passing through its centre and perpendicular to its plane is 100 gm.cm². Then, its M.I. about its diameter is...
[A] 100 gm.cm² 
[B] 50 gm.cm² 
[C] 200 gm.cm² 
[D] 25 gm.cm2
Answer: D

Question. A ring , a disc and a sphere, all of same mass and radius, rotate with the same angular velocity about their diameter. Which has maximum rotational kinetic energy?
[A] Ring
[B] Disc
[C] Sphere
[D] All have same kinetic energy
Answer: B

Question. If the earth stops rotating, the value of 'g' will...
[A] increase
[B] decrease
[C] not change
[D] become zero
Answer: A

Question. A parrot resting on a floor of an air-tight box, which is being carried by a girl starts flying. The girl will feel that the box...
[A] is now lighter
[B] is now heavier
[C] shows no change in weight
[D] is also flying
Answer: A

Question. The thermal resistance of a metal block of length l, area of cross-section A and thermal conductivity k is...
[A] l/(k.A)
[B] l.A/k
[C] k.A/l
[D] k.l/A
Answer: C

Question. The equivalent thermal conductivity of a slab consisting of two parallel layers of two different materials of thermal conductivity K₁ and K₂ is...
[A] K₁ + K₂ 
[B] K₁.K₂ 
[C] (K₁ + K₂)/2
[D] (2K₁ + K₂)/(K₁ + K₂)
Answer: A

Question. A sphere, a cube and a thin circular plate, all made of same material and of same mass are heated to a temperature of 100°C. Which of these cools faster when left in air at room temperature?
[A] Sphere
[B] Circular plate
[C] Cube
[D] All of them at the same rate
Answer: B

Question. No energy is transmitted in a...
[A] longitudinal progressive wave
[B] stationary wave
[C] transverse progressive wave
[D] electromagnetic wave
Answer: B

Question. The velocity of sound in air is V. At what speed a source must travel towards a listener at rest so that the apparent frequency heard is double the true frequency of the source?
[A] V/2
[B] V/4
[C] 2V
[D] 4V
Answer: A

Question. A spring with force constant k is cut in half. Each of the new springs has a force constant of...
[A] k/2
[B] k
[C] 2k
[D] √ 2.k
Answer: C

Question. A harmonic oscillator of mass 40 g has a period of 10 seconds. To reduce the period to 5 seconds, the mass should be changed to...
[A] 10 g
[B] 20 g
[C] 80 g
[D] 160 g
Answer: A

Question. An example of a purely longitudinal wave is...
[A] a sound wave
[B] an electromagnetic wave
[C] a water wave
[D] a wave in a stretched string
Answer: D

Question. The quality, or timbre, of a musical sound is due to...
(a) its fundamental frequency
(b) its overtone structure
(c) its amplitude
(d) the presence of beats
Answer: B

Question. If θ is the inclination and μ_s, the coefficient of static friction, then a cylinder can roll on the inclined plane without slipping for...
(a) μ_s ≥ tanθ
(b) μ_s ≥ (tanθ)/3
(c) μ_s ≥ (1/tanθ)
(d) μ_s ≥ (1/3tanθ)
Answer: B

Question. The moment of inertia of a rigid body is...
(a) always constant
(b) does not change generally
(c) depends on number of particles
(d) different for different axes
Answer: D

Question. Ball A is thrown horizontally and ball B is dropped from the same height at the same moment. Then...
(a) A reaches the ground first
(b) B reaches the ground first
(c) A has greater speed when it reaches the ground
(d) B has greater speed when it reaches the ground
Answer: C

Question. If for the planets in the solar system, r is the radius of the orbit and T is the periodic time, then the ratio r³/t² is...
(a) 1
(b) same for all planets
(c) more for farther planets
(d) less for farther planets
Answer: B

Question. The adiabatic equation for the ideal gas, PVγ = constant can also be written as...
(a) PV = γ
(b) PT^γ = constant
(c) T^γ/P^{γ - 1} = constant
(d) PV^γT^γ = R
Answer: C

Question. In any process, the maximum amount of mechanical energy that can be converted to heat...
(a) depends only on the intake temperature
(b) depends only on the exhaust temperature
(c) depends on the compression ratio
(d) is 100%
Answer: D

Question. Electrical energy in the form of electric current is converted into _____ when a storage battery is charged.
(a) electrical
(b) thermal
(c) chemical
(d) light
Answer: C

Question. The power consumed by a resistance that obeys Ohm's law is given by...
(a) P = V²/R
(b) P = V²R
(c) P = IR
(d) P = IR²
Answer: A

Question. Faraday's constant is...
(a) 96487 coulomb/g
(b) 96487 coulomb/mole
(c) 964870 coulomb/g
(d) 964870 coulomb/mole
Answer: B

Question. When the lead storage cell is fully charged, its voltage and specific gravity of electrolyte, respectively are...
(a) 2.1 V, 1.825
(b) 1.5 V, 1.825
(c) 2.1 V, 1.285
(d) 1.5 V, 1.285
Answer: C

Question. A voltmeter should have a very ____ resistance and should be connected in ____.
(a) large, parallel
(b) large, series
(c) small, parallel
(d) small, series
Answer: A

Question. I₁ and I₂ are currents in primary and secondary coils respectively, of a step-up transformer. Then...
(a) I₁ is smaller than I₂
(b) I₁ is smaller than or equal to I₂
(c) I₁ is greater than I₂
(d) I₁ greater than or equal to I₂
Answer: C

Question. If A is the area of a coil of N turns rotating with angular speed ω in a uniform magnetic field B, then the instantaneous value of e.m.f. generated in the coil is...
(a) NABω
(b) NABω sint
(c) NABω sinωt
(d) NABω cost
Answer: C

Question. In an LCR circuit resonance occurs at the frequency for which...
(a) X_L > X_C
(b) X_L < X_C
(c) X_L - X_C = 0
(d) X_L = 0
Answer: C

Question. λ (wavelength) of visible light is...
(a) more than λ of ultraviolet light
(b) more than λ of infra-red light
(c) less than λ of X-rays
(d) more than λ of microwaves
Answer: A

Question. The phase difference between two waves superimposing at a point for destructive interference to occur should be...
(a) nπ
(b) 2nπ
(c) (2n + 1)π/2
(d) (2n + 1)π
Answer: D

Question. Diffraction in visible light is harder to observe because of...
(a) low frequencies
(b) high velocity
(c) visibility
(d) short wavelength
Answer: D

Question. The charge to mass ratio (specific charge) for an electron (in coulomb/kg) is approximately equal to...
(a) 1.76 x 10^-11 
(b) 1.76 x 10¹¹ 
(c) 1.76 x 10^-8 
(d) 1.76 x 10⁸
Answer: B

Question. If V_s is the stopping potential and e is the charge on electron, the energy required by the electron to cross over this potential difference is...
(a) V_s/e²
(b) V_s/e
(c) (V_s)²/e
(d) V_s . e
Answer: D

Question. The change of energy level is always accompanied by the emission or absorption of radiation depending upon the size of...
(a) the energy change
(b) the atom
(c) the nucleus
(d) the electron
Answer: A

Question. In the hydrogen spectrum, the series obtained in the ultraviolet region is...
(a) Balmer series
(b) Lyman series
(c) Paschen series
(d) Pfund series
Answer: B

Question. In an N-type semiconductor...
(a) free electron density exceeds hole density
(b) hole density exceeds free electron density
(c) free electrons are absent
(d) holes are absent
Answer: A

Question. A diode allows electric current...
(a) to increase
(b) to decrease
(c) to flow in one direction only
(d) to flow alternately in both directions
Answer: C

Question. Two forces 2i - 3j and _____ have a resultant 5i + 4j.
(a) 7i + j
(b) -3i - 7j
(c) 3i + 7j [
D] 7i + 7j
Answer: C

Question. If the magnitude of electromagnetic force is 1, the relative strength of strong force is...
(a) 10^-2 
(b) 10^-1 
(c) 10
(d) 10²
Answer: D

Question. During an interaction of two particles, the changes produced in velocity are always...
(a) constant
(b) equal for both particles
(c) in opposite directions
(d) in direct proportion to their weights
Answer: C

Question. Which of the following is not a unit of power?
(a) joule.second
(b) watt
(c) horsepower
(d) newton.meter/second
Answer: A

Question. A 1 kg mass has a P.E. of 1 joule relative to the ground when it is at a height of about...
(a) 0.12 m
(b) 1.0 m
(c) 9.8 m
(d) 32 m
Answer: A

Question. An object in motion need not have...
(a) velocity
(b) momentum
(c) K.E.
(d) P.E.
Answer: D