Physics - Online Test
Q1. According to the principle of homogeneity of dimensions
Answer : Option C
Explaination / Solution:
It would be more exact to say that "Quantities with the same units can be added and subtracted with no problem." Quantities with the same dimensions can often be added and subtracted as long as the units are correctly converted.
Q2. A Wheatstone bridge is balanced for four resistors R1, R2, R3 and R4 with a Lech lanche cell between A and C and a galvanometer between B and D. The positions of the cell and the galvanometer are interchanged. The balance will
Answer : Option A
Explaination / Solution:
The balance point will not change .
For balancing of wheatstone bridge four arms of resistors are responsible. Interchange the position of galvanometer and cell does not affect balancing of wheatstone bridge.
Q3. At resonance conditons when the forced vibrations frequency matches the natural frequency of the system, amplitude __________________ the natural frequency of the oscillator.
Answer : Option C
Explaination / Solution:
When the mass and spring have no external force acting on them they transfer energy back and forth at a rate equal to the natural frequency. In other words, to efficiently pump energy into both mass and spring requires that the energy source feed the energy in at a rate equal to the natural frequency. Applying a force to the mass and spring is similar to pushing a child on swing, a push is needed at the correct moment to make the swing get higher and higher. As in the case of the swing, the force applied need not be high to get large motions, but must just add energy to the system.
The damper, instead of storing energy, dissipates energy. Since the damping force is proportional to the velocity, the more the motion, the more the damper dissipates the energy. Therefore, there is a point when the energy dissipated by the damper equals the energy added by the force. At this point, the system has reached its maximum amplitude and will continue to vibrate at this level as long as the force applied stays the same. If no damping exists, there is nothing to dissipate the energy and, theoretically, the motion will continue to grow into infinity.
Q4. Diffraction also refers to
Answer : Option C
Explaination / Solution:
No Explaination.
Q5. In Ferromagnetic materials
Answer : Option B
Explaination / Solution:
No Explaination.
Q6. For Geostationary Satellites
Answer : Option C
Explaination / Solution:
If there is a satellite in the equatorial plane rotating in the direction of earth’s rotation from west to east, then for an observer, on the earth, angular velocity of satellite will be
The time interval between the two consecutive appearances overhead will be,
If , i.e. satellite will appear stationary relative to earth. Such satellites are called geostationary satellites and will have a period of rotation as the period of rotation of earth i.e 24 Hrs.
Q7. The main difference between conductors, semiconductors and insulators is because of
Answer : Option C
Explaination / Solution:
Forbidden gap plays a major role for determining the electrical conductivity of material. Based on the forbidden gap materials are classified in to three types, they are :
- Insulators : The forbidden gap between the valence band and conduction band is very large in insulators. The energy gap of insulator is approximately equal to 15 electron volts (eV).
- Conductors: In a conductor, valence band and conduction band overlap each other. Therefore, there is no forbidden gap in a conductor.
- Semiconductors: In semiconductors, the forbidden gap between valence band and conduction band is very small. It has a forbidden gap of about 1 electron volt (eV).
Q8. A car moving at 60 km/h comes to a stop in 4.0 s. What was its deceleration?
Answer : Option C
Explaination / Solution:
initial velocity u = 60 m/s
As it stop final velocity v = 0
Time taken t = 4 s
We know,
Negative sign shows it is declaration.
Q9. Two sinusoidal waves on the same string exhibit interference, adding or cancelling according to the principle of superposition. If the two are travelling in the same direction and have the same amplitude a and frequency but differ in phase by a phase constant φ, the result is a single wave with the same frequency ωω :If φ = 0 or an integral multiple of 2 π ,
Answer : Option B
Explaination / Solution:
No Explaination.
Q10. Tanning of the skin in sunlight is due to
Answer : Option A
Explaination / Solution:
No Explaination.
