Physics - Online Test
Q1. Emission and absorption is best described by,
Answer : Option A
Explaination / Solution:
No Explaination.
Q2. When iron filings are sprinkled on a sheet of glass placed over a short bar magnet then,
Answer : Option D
Explaination / Solution:
North pole act as positive end and South pole act as negative end. The iron fillings in the presence of magnetic field gets magnetized and form a tiny magnet which then gets attracted to the poles of bar magnet. North pole of bar magnet attracts south pole of tiny magnet and vice-versa. So all the iron fillings are arranged as the magnetic field lines of bar magnet.
Q3. According to Kepler’s Law of periods, The _______________ of the time period of revolution of a planet is proportional to the cube of the ___________ of the ellipse traced out by the planet
Answer : Option B
Explaination / Solution:
Kepler's 3rd Law: T2 = a3. Kepler's 3rd law is a mathematical formula. It means that if you know the period of a planet's orbit (T = how long it takes the planet to go around the Sun), then you can determine that planet's distance from the Sun (a is the length of the semimajor axis of the planet's orbit)
Q4. In the case of semiconductors the valence and conduction bands have
Answer : Option C
Explaination / Solution:
The materials can be classified by the energy gap between their valence band and the conduction band. The valence band is the band consisting of the valence electron, and the conduction band remains empty. Conduction takes place when an electron jumps from valence band to conduction band and the gap between these two bands is forbidden energy gap. Wider the gap between the valence and conduction bands, higher the energy it requires for shifting an electron from valence band to the conduction band.
- In the case of conductors, this energy gap is absent or in other words conduction band, and valence band overlaps each other. Thus, electron requires minimum energy to jump from valence band. The typical examples of conductors are Silver, Copper, and Aluminium.
- In insulators, this gap is vast. Therefore, it requires a significant amount of energy to shift an electron from valence to conduction band. Thus, insulators are poor conductors of electricity. Mica and Ceramic are the well-known examples of insulation material.
- Semiconductors, on the other hand, have an energy gap which is in between that of conductors and insulators. This gap is typically more or less 1 eV, and thus, one electron requires energy more than conductors but less than insulators for shifting valence band to conduction band.
Q5. Path length is defined as.
Answer : Option B
Explaination / Solution:
Path length is defined as the total length of the path traversed by an object.
Unlike displacement, which is the total distance an object travels from a starting point, path length is the total distance travelled, regardless of where it travelled.
Q6. Without the concept of displacement current it is not possible to correctly apply Ampere’s law on a path parallel to the plates of parallel plate capacitor C in
Answer : Option B
Explaination / Solution:
No Explaination.
Q7. Electromagnetic waves are different from sound waves in that
Answer : Option C
Explaination / Solution:
Electromagnetic waves are transverse waves, they move perpendicular to the direction of propagation of wave ( the direction in which energy is transferred) and EM waves( Electromagnetic waves) can travel in vacuum, thus doesn't require any medium also.
Q8. In rotation of a rigid body about a fixed axis is that in which
Answer : Option A
Explaination / Solution:
When a rigid body rotates about a fixed axis, all particles of the body except those which lies on the axis of rotation, move along circular paths in a plane perpendicular to the axis.
Q9.
When current carrying coil is moved towards the coil connected in series with a galvanometer, the pointer in the galvanometer G
Answer : Option C
Explaination / Solution:
current induced due to flux changed when C2 is in motion .
Q10. Photoelectric effect is
Answer : Option B
Explaination / Solution:
When the light strikes on a metal surface, electrons on the surface of the metal get energy from the light and get emitted from the surface. It is found that there will be no photoemission from a metal surface below a certain frequency of light. The phenomenon of emission of photoelectron from a metal surface by light of suitable frequency is called photoelectric effect.
