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**General Physics Quiz | objective questions | Physics General Knowledge Questions | MCQ**

**1 >>Four solid spheres each of diameter 5**

^{1/2}cm and mass 0.5 kg are placed with their centers at the corners of a square of side 4cm. The moment of inertia of the system about the diagonal of the square is N x 10-4 kg -m^{2}, then N is ?- (A) 9
- (B) 8
- (C) 7
- (D) 6

**2 >>A long circular tube of length 10 m and radius 0.3 m carries a current I along its curved surface as shown. A wire-loop of resistance 0.005 ohm and of radius 0.1 m is placed inside the tube with its axis coinciding with the axis of the tube. The current varies as I = I**

_{o}cos(300 t) where I_{o}is constant. If the magnetic moment of the loop is Nu_{o}I_{o}sin 300t , then ’N’ is ?- (A) 6
- (B) 7
- (C) 8
- (D) 9

**3 >>Four point charges, each of +q, are rigidly fixed at the four corners of a square planar soap film of side ’ α ’. The surface tension of the soap film is γ . The system of charges and planar film are in equilibrium, the a =(q**

^{2}/(γ))^{1/N},where ’˜k’ is a constant. Then N is ?- (A) 3
- (B) 4
- (C) 5
- (D) 6

**4 >>Radiocarbon is produced in the atmosphere as a result of ?**

- (A) collision between fast neutrons and nitrogen nuclei present in the atmosphere
- (B) action of ultraviolet light from the sun on atmospheric oxygen
- (C) action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere
- (D) lightning discharge in atmosphere

**5 >>It is easier to roll a stone up a sloping road than to lift it vertical upwards because ?**

- (A) work done in rolling is more than in lifting
- (B) work done in lifting the stone is equal to rolling it
- (C) work done in both is same but the rate of doing work is less in rolling
- (D) work done in rolling a stone is less than in lifting it

**6 >>The absorption of ink by blotting paper involves ?**

- (A) viscosity of ink
- (B) capillary action phenomenon
- (C) diffusion of ink through the blotting
- (D) siphon action

**7 >>Siphon will fail to work if ?**

- (A) the densities of the liquid in the two vessels are equal
- (B) the level of the liquid in the two vessels are at the same height
- (C) both its limbs are of unequal length
- (D) the temperature of the liquids in the two vessels are the same

**8 >>Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to ?**

- (A) the heating effect of current alone
- (B) hysteresis loss alone
- (C) both the heating effect of current and hysteresis loss
- (D) intense sunlight at noon

**9 >>Nuclear sizes are expressed in a unit named ?**

- (A) Fermi
- (B) angstrom
- (C) newton
- (D) tesla

**10 >>Light year is a unit of ?**

- (A) time
- (B) distance
- (C) light
- (D) intensity of light

**11 >>Mirage is due to ?**

- (A) unequal heating of different parts of the atmosphere
- (B) magnetic disturbances in the atmosphere
- (C) depletion of ozone layer in the atmosphere
- (D) equal heating of different parts of the atmosphere

**12 >>Light from the Sun reaches us in nearly ?**

- (A) 2 minutes
- (B) 4 minutes
- (C) 8 minutes
- (D) 16 minutes

**13 >>Stars appears to move from east to west because ?**

- (A) all stars move from east to west
- (B) the earth rotates from west to east
- (C) the earth rotates from east to west
- (D) the background of the stars moves from west to east

**14 >>Pa(Pascal) is the unit for ?**

- (A) thrust
- (B) pressure
- (C) frequency
- (D) conductivity

**15 >>Planets do not twinkle because ?**

- (A) they emit light of a constant intensity
- (B) their distance from the earth does not change with time
- (C) they are very far away from the earth resulting in decrease in intensity of light
- (D) they are nearer to earth and hence we receive a greater amount of light and, therefore minor variations in the intensity are not noticeable

**16 >>Metals are good conductors of electricity because ?**

- (A) they contain free electrons
- (B) the atoms are lightly packed
- (C) they have high melting point
- (D) All of these

**17 >>Let a thin capillary tube be replaced with another tube of insufficient length then, we find water ?**

- (A) will overflow
- (B) will not rise
- (C) depressed
- (D) change its meniscus

**18 >>Out of the following pairs, choose the pair in which the physical quantities do not have identical dimension? ?**

- (A) Pressure and Young's modules
- (B) Planck's constant and Angular momentum
- (C) Impulse and moment of force
- (D) Force and rate of change of linear momentum

**19 >>If two bodies of different masses, initially at rest, are acted upon by the same force for the same time, then the both bodies acquire the same ?**

- (A) velocity
- (B) momentum
- (C) accelaration
- (D) kinetic energy

**20 >>Pick out the scalar quantity ?**

- (A) force
- (B) pressure
- (C) velocity
- (D) accelaration

**1 >>The wavelength of the first spectral line in the Balmer series of hydrogen atom is 6561 A**

atom is ?

^{o},The wavelength of the second spectral line in the Balmer series of singly-ionized heliumatom is ?

- (A) 1215A
^{o} - (B) 1640A
^{o} - (C) 2430A
^{o} - (D) 4687A
^{o}

**22 >>A ball of mass (m) 0.5 kg is attached to the end of a string having length (L) 0.5 m. The ball is**

rotated on a horizontal circular path about vertical axis. The maximum tension that the string

can bear is 324 N. The maximum possible value of angular velocity of ball (in radian/s) is ?

rotated on a horizontal circular path about vertical axis. The maximum tension that the string

can bear is 324 N. The maximum possible value of angular velocity of ball (in radian/s) is ?

- (A) 9
- (B) 18
- (C) 27
- (D) 36

**23 >>A meter bridge is set-up as shown, to determine an unknown resistance ’X’ using a standard**

10 ohm resistor. The galvanometer shows null point when tapping - key is at 52 cm mark.

The end-corrections are 1 cm and 2cm respectively for the ends A and B. The determined

value of ’X’ is ?

10 ohm resistor. The galvanometer shows null point when tapping - key is at 52 cm mark.

The end-corrections are 1 cm and 2cm respectively for the ends A and B. The determined

value of ’X’ is ?

- (A) 10.2 ohm
- (B) 10.6 ohm
- (C) 10.8 ohm
- (D) 11.1 ohm

**24 >>A 2uF capacitor is charged as shown in figure. The percentage of its stored energy dissipated**

after the switch S is turned to position 2 is ?

after the switch S is turned to position 2 is ?

- (A) 0
- (B) 0.2
- (C) 0.75
- (D) 0.8

**25 >>A police car with a siren of frequency 8kHz is moving with uniform velocity 36km/hr towards**

a tall building which reflects the sound waves. The speed of sound in air is 320 m/s. The

frequency of the siren heard by the car driver is ?

a tall building which reflects the sound waves. The speed of sound in air is 320 m/s. The

frequency of the siren heard by the car driver is ?

- (A) 8.50 kHz
- (B) 8.250 kHz
- (C) 7.750 kHz
- (D) 7.50 kHz

**26 >>5.6 liter of helium gas at STP is adiabatically compressed to 0.7 liter. Taking the initial temperature to be T**

^{1}, the work done in the process is ?- (A) 9/8 RT
^{1} - (B) 3/2 RT
^{1} - (C) 15/8 RT
^{1} - (D) 9/2 RT
^{1}

**27 >>Consider an electric field E= E**

_{o}xË†, where E_{o}is a constant. The flux through the shaded area (as shown in the figure) due to this field ?- (A) 2E
_{o}a^{2} - (B) (2)
^{1/2}E_{o}a^{2} - (C) E
_{o}a^{2} - (D) E
_{o}a^{2}/((2)^{1/2})

**28 >>A metal rod of length’L’ and mass’m’ is pivoted at one end. A thin disk of mass ’M’ and radius’R’(**

**(A) Restoring torque in case A = Restoring torque in case B****(B) Restoring torque in case A < Restoring torque in case B****(C) Angular frequency for case A > Angular frequency for case B****(D) Angular frequency for case A = Angular frequency for case B**

**29 >>A composite block is made of slabs A, B, C, D and E of different thermal conductivities (given in terms of a constant K) and sizes (given in terms of length, L) as shown in the figure. All slabs are of same width. Heat ’Q’ flows only from left to right through the blocks. Then in steady state ?****(A) heat flow through A and E slabs are same**- (B) heat flow through slab E is minimum
- (C) temperature difference across slab E is largest
- (D) heat flow through C > (heat flow through B + heat flow through D)

**30 >>An electron and a proton are moving on straight parallel paths with same velocity. They enter a semi-infinite region of uniform magnetic field perpendicular to the velocity. Which of the following statement(s) is/are true ? ?****(A) They will never come out of the magnetic field region**- (B) They will come out travelling along parallel paths
- (C) They will come out at the same time
- (D) None of these

**31 >>A spherical metal shell A of radius R**_{A}and a solid metal sphere B of radius R_{B}(< R_{A}) are kept far apart and each is given charge ’+Q’. Now they are connected by a thin metal wire.Then ?- (A) E
_{A}^{inside}> 0 - (B) Q
_{A}< Q_{B} - (C) ((σ
_{A})/(σ_{B})) = ((R_{A})/(R_{B})) - (D) E
_{A}^{on surface}> E_{B}^{on surface}

**32 >>A dense collection of equal number of electrons and positive ions is called neutral plasma. Certain solids containing fixed positive ions surrounded by free electrons can be treated as neutral plasma. Let ’˜N’ be the number density of free electrons, each of mass ’˜m’. When the electrons are subjected to an to electric field, they are displaced relatively away from the heavy positive ions. If the electric field becomes zero, the electrons begin to oscillate about the positive ions with a natural angular frequency ' /omega**

_{p}' which is called the palsma frequency. To sustain the oscillations, a time varying electric field needs to be applied that has an angular frequency /omega , where a part of the energy is absorbed and a part of it is reflected. As /omega approaches /omega_{p}, all the free electrons are set to resonance together and all the energy is reflected. This is the explanation of high reflectivity metals.**Taking the electric charge as 'e' and the permittivity as /omega**?_{o}' , use dimesional analysis to determine the correct expression for /omega_{p}.- (A) ((Ne)/(mE
_{o}))^{1/2}

_{o})/(Ne))

^{1/2}

^{2})/(mE

_{o}))

^{1/2}

_{o})/(Ne

^{2}))

^{1/2}

= (((1/L

^{3})*(I

^{2}T

^{2})*(ML

^{3}T

^{-2}))/(M*(I

^{2}T

^{2})))

=> D.f = T

^{-1}

**33 >>A dense collection of equal number of electrons and positive ions is called neutral plasma. Certain solids containing fixed positive ions surrounded by free electrons can be treated as neutral plasma. Let ’N’ be the number density of free electrons, each of mass ’˜m’. When the electrons are subjected to an to electric field, they are displaced relatively away from the heavy positive ions. If the electric field becomes zero, the electrons begin to oscillate about the positive ions with a natural angular frequency ' /omega**

_{p}' which is called the palsma frequency. To sustain the oscillations, a time varying electric field needs to be applied that has an angular frequency /omega , where a part of the energy is absorbed and a part of it is reflected. As /omega approaches /omega_{p}, all the free electrons are set to resonance together and all the energy is reflected. This is the explanation of high reflectivity metals.**Estimate the wavelength at which plasma reflection will occur for a metal having the density of electrons N = 4*10**?^{27}m^{-3}. Take E_{o}= 10^{-11}and m =10^{-30}, where these quantities are in proper SI units.- (A) 800nm
- (B) 600nm
- (C) 300nm
- (D) 200nm

**34 >>Newton's 1st Law is the law of ?**

- (A) Inertia
- (B) Force
- (C) Momentum
- (D) Acceleration

**35 >>For additional info, click on the i button above. The phase space diagram for simple harmonic motion is a circle centered at the origin. In the figure, the two circles represent the same oscillator but for different initial conditions, and E1 and E2 are the total mechanical energies respectively. Then, ?**

- (A) E
_{1}= 2^{1/2}E_{2} - (B) E
_{1}= E_{2} - (C) E
_{1}= 4E_{2} - (D) E
_{1}= 16E_{2}

**36 >>The conduction current in a chemical cell is ?**

- (A) By Positive and negative ions
- (B) By Positive ions
- (C) By Negative ions
- (D) By Positive Holes

**37 >>Steel wire of length ’L’ at 40°C is suspended from the ceilling and then a mass ’m’ is hung from its free end. The wire is cooled down from 40°C to 30°C to regain its original length ’˜L’. The coefficient of liner thermal expansion of the steel is 10’“5/°C, Young’s modulus of steel is 1011 N/m**

^{2}and radius of the wire is 1mm. Assume that L>> diameter of the wire. Then the value of ’˜m’ in kg is nearly ?- (A) 3
- (B) 4
- (C) 5
- (D) 6

**38 >>The activity of a freshly prepared radioactive sample is 10**

^{10}disintegrations per second, whose mean life is 10^{9}s. The mass of an atom of this radioisotope is 10^{-23}kg. The mass (in mg) of the radioactive sample is ?- (A) 1
- (B) 2
- (C) 3
- (D) 4

**39 >>A block moving on an inclined plane making an angle 45° with the horizontal and the coefficient of friction is u . The force required to just push it up the inclined plane is 3 times the force required to just prevent from sliging down. If we define N = 10u then N is ?**

- (A) 5
- (B) 6
- (C) 7
- (D) 9

**40 >>A boy is pushing a ring of mass 2 kg and radius 0.5 m with a stick a shown in the figure. Then stick applies a force of 2 N on the ring and rolls it without slipping with an acceleration of 0.3m/s2. The coefficient of friction between the ground and the ring is large enough that rolling always occurs and the coefficient of friction between the stick and the ring is (P/10). The value of P is ?**

- (A) 4
- (B) 5
- (C) 6
- (D) 7