Physics - Online Test
Q1. The time period T of a spring system of mass m and spring constant k is given by
Answer : Option D
Explaination / Solution:
If the restoring force of a vibrating or oscillatory system is proportional to the displacement
of the body from its equilibrium position and is directed opposite to the direction of displacement,
the motion of the system is simple harmonic and it is given by
where A, the maximum value of the displacement, is called the amplitude of the motion. If
T is the time for one complete oscillation, then
x(t + T) = x(t)
or
As angular frequency is given by and
Then,time period of oscillation of mass m is given by
Q2. Two sources of light are coherent if they have
Answer : Option A
Explaination / Solution:
No Explaination.
Q3. considering the magnetic field of the earth,the correct relation of the geographic pole and the magnetic poles is
Answer : Option A
Explaination / Solution:
No Explaination.
Q4. The force of attraction due to a hollow spherical shell of uniform density, on a point mass situated inside it, is
Answer : Option B
Explaination / Solution:
The gravitational force acting by a spherically symmetric shell upon a point mass inside it, is the vector sum of gravitational forces acted by each part of the shell, and this vector sum is equal to zero. That is, a mass m within a spherically symmetric shell of mass M will feel no net force
Q5. in n-type semiconductor majority carriers and minority carriers are respectively
Answer : Option B
Explaination / Solution:
N-type semiconductors have a larger electron concentration than hole concentration. The term n-type comes from the negative charge of the electron.
In n-type semiconductors, electrons are the majority carriers and holes are the minority carriers.
N-type semiconductors are created by doping an intrinsic semiconductor with donor impurities (or doping a p-type semiconductor as done in the making of CMOS chips). A common dopant for n-type silicon is phosphorus.
Q6. Average speed is defined as the total path length travelled divided by the total time interval during which
Answer : Option A
Explaination / Solution:
Average speed is the ratio of distance traveled to time spent.
To find average speed, divide the total number of km traveled by the total elapsed time in hours. The answer is the average speed in km per hour.
Q7. Magnitude of the electric and the magnetic fields in an plane electromagnetic wave are related by
Answer : Option B
Explaination / Solution:
No Explaination.
Q8. If y(x, t) = a sin (kx + ωt + φ) represents a wave function
Answer : Option B
Explaination / Solution:
On comparing above equation with
y(x, t) = a sin (-kx + ωt + φ), we get
Distance traveled by wave is along - x axis
Hence y(x, t) = a sin (kx + ωt + φ) represents a wave function
travelling in the -ve x direction
Q9. A rectangular conductor PQRS in which the conductor PQ is free to move is kept in a magnetic field B ,which is perpendicular to the PQRS which lies in a single plane. If the conductor PQ has a length l,moves with a speed v, then induced emf is
Answer : Option B
Explaination / Solution:
e=dϕdt=d(BS)dt=B.dsdt=Bl.dxdt=Blv
Q10. According to the Einstein’s model minimum energy needed for the electron to escape from a metal surface having work function , the electron is emitted with maximum kinetic energy =
Answer : Option D
Explaination / Solution:
When any photon is incident on a metal surface it gives its total energy to a electron. Some energy(Work Function) is used up in come out from the metal surface and remaining energy is kinetic energy of electron.
