Multiple choice question for engineering
1. A motion can be periodic and not oscillatory. True or false?
2. A simple pendulum of length l and with a bob whose mass is m is moving along a circular arc of angle θ in a vertical plane. A sphere of mass m is placed at the end of the circle. What momentum will be given to the sphere by the moving bob?
3. When a 2 kg body is suspended by a spring, the spring is stretched. If the body is pulled down slightly and released, it oscillates up and down. What force is applied on the body by the spring when it passes through the mean position?
a) Force equal to the gravity
b) Force equal to the pull
c) Conservative force
d) Force equal to the weight of the body
4. The displacement of an object attached to a spring and executing simple harmonic motion is given by
x=2×10-2 cosπt(in m)
The time at which the maximum speed first occurs is
5. The maximum velocity of a particle, executing simple harmonic motion with amplitude 7mm, is 4.4m/s. The period of oscillation is
6. If the frequency of oscillation of a particle doing simple harmonic motion is n, the frequency of kinetic energy is
7. Natural length of spring is 60 cm and its spring constant is 4000 N/m. A mass of 20 kg is hung from it. The extension produced in the spring (take g=9.8m/s2) is
8. The phase difference between the instantaneous velocity and acceleration of a particle executing simple harmonic motion is
c) 0.707 π
d) 0.61 π
9. A horizontal platform with an object placed on it is executing simple harmonic motion in the vertical direction. The amplitude of oscillation is 3.92×10-3 m. What must be the least period of these oscillations, so that the object is not detached from the platform?
10. Statement: The amplitude of an oscillating pendulum decreases gradually with time [Reason:] The frequency of the pendulum decreases with time
a) Both statement and reason are true and reason is the correct explanation of the statement
b) Both statement and reason are true but reason is not the correct explanation of the statement
c) Statement is true, but reason is false
d) Statement and reason are false
1. The ratio of velocity of sound in hydrogen and oxygen at STP is
2. It takes 2 seconds for a sound wave to travel between two fixed points when the day temperature is 10°C. If the temperature rises to 30°C, the sound wave travels between the same fixed parts in
3. The disc of a siren containing 60holes rotates at a constant speed of 360rpm. The emitted sound is in unison with a tuning fork of frequency
4. The quantity which does not change, when sound enters from one medium to another
5. The equation of a simple harmonic wave is given by
Where x and y are in metre and time is in second. The period of the wave in second will be
6. If wave y=Acos(ωt+kx) Is moving along x-axis, the shapes of pulse at t=0 and t=2s
a) Are different
b) Are same
c) May not be the same
7. y1=4sin(ωt+kx), y2=-4cos(ωt+kx), the phase difference is
8. A wave equation is y=0.1sin[100πt-kx] and wave velocity is 100m/s, its number is equal to
9. A particle on the trough of a wave at any instant will come to the mean position after a time (T=time period)
10. A string is tied on a sonometer, second end is hanging downward through a pulley with tension T. The velocity of the transverse wave produced is proportional to
11. The fundamental frequency of a sonometer wire is n. If the tension is made 3 times and length and diameter are also increased 3 times, the new frequency will be
d) √3 n
1. What is the process of producing electric dipoles inside the dielectric by an external electric field?
b) Dipole moment
2. Which of the following easily adapt itself to store electrical energy?
a) Passive dielectric
c) Active dielectric
d) Polar molecules
3. Which of the following restricts the flow of electrical energy?
b) Passive dielectrics
c) Polar molecules
d) Active dielectric
4. For non-polar molecules, there is no absorption or emission in the range of infrared. True or false?
5. How does ionic polarisation occur?
a) Splitting of ions
b) Passing magnetic field
c) Displacement of cations and anions
d) Never occurs
6. Polar molecules have permanent dipole moments even in the absence of an electric field. True or false?
7. Which of the following polarisations is very rapid?
a) Electronic polarisation
b) Ionic polarisation
c) Space charge polarisation
d) Orientation polarisation
8. Which of the following is the slowest polarisation method?
a) Ionic polarisation
b) Orientation polarisation
c) Electronic polarisation
d) Space charge polarisation
9. When does a dielectric become a conductor?
a) At avalanche breakdown
b) At high temperature
c) At dielectric breakdown
d) In the presence of magnetic field
10. Which of the following breakdowns occur at higher temperature?
a) Avalanche breakdown
b) Thermal breakdown
c) Electrochemical breakdown
d) Dielectric breakdown
11. When mobility increases, insulation resistance decreases and dielectric becomes conducting. True or false?
12. Which of the following materials exhibit Ferro-electricity?
d) Rochelle salt
13. Calculate the electronic polarizability of an argon atom whose ɛr = 1.0024 at NTP and N = 2.7×1025 atoms/m3.
a) 0.0024 Fm2
b) 7.87 ×10-40 Fm2
c) 7.87 Fm2
d) 1.0024×10-40 Fm2
14. Calculate the dielectric constant of a material which when inserted in parallel condenser of area 10mm × 10mm and distance of separation of 2mm, gives a capacitance of 10-9 F.
15. Find the capacitance of layer of A13 O3 that is 0.5μm thick and 2000mm2 of square area εr = 8.
1. How does a semiconductor behave at absolute zero?
d) Protection device
2. Semiconductor acts as an insulator in the presence of impurities. True or false?
3. How is the resistance of semiconductor classified?
a) High resistance
b) Positive temperature co-efficient
c) Negative temperature co-efficient
d) Low resistance
4. What are the charge carriers in semiconductors?
a) Electrons and holes
5. Which of the following is known as indirect band gap semiconductors?
6. Which column elements are combined to make compound semiconductors?
a) First and fourth
b) Fifth and sixth
c) Second and fourth
d) Third and fifth
7. Compound semiconductors are also known as direct bad gap semiconductors. True or false?
8. How is charge carriers produced in intrinsic semiconductors?
a) By pure atoms
b) By electrons
c) By impure atoms
d) By holes
9. What type of material is obtained when intrinsic semiconductor is doped with pentavalent impurity?
a) N-type semiconductor
b) Extrinsic semiconductor
c) P-type semiconductor
10. What type of material is obtained when an intrinsic semiconductor is doped with trivalent impurity?
a) Extrinsic semiconductor
c) N-type semiconductor
d) P-type semiconductor
1. If no external torque acts on a body, its angular velocity remains conserved. True or false?
2. Which component of linear momentum does not contribute to angular momentum?
a) Horizontal component
b) Vertical component
c) Radial component
d) Tangential component
3. A heavenly body revolves around a massive star in a highly elliptical orbit. Ignoring mass loss of the heavenly body when it comes too close to the star, the angular momentum over the orbit is
4. A body can be in equilibrium while it is in motion. True or false?
5. We can rise from a chair without bending a little forward. True or false?
6. When a cat falls from a height
a) It sustains injury
b) It dies
c) It lands on its feet
d) It bounces back
7. How many propellers are there in a helicopter?
b) No propellers
8. If earth were to shrink suddenly, what would happen to the length of the day?
a) It increases
b) It remains the same
c) It decreases
d) It becomes unpredictable
9. A child is sitting on a swing. Its minimum and maximum heights from the ground 0.75m and 2m respectively, its maximum speed will be
a) 10 m/s
b) 5 m/s
c) 8 m/s
d) 15 m/s
10. A moving body of mass m and velocity 3km/h collides with a rest body of mass 2m and strikes to it. Now the combined mass starts to move. What will be the combined velocity?