Physics - Online Test
Q1.
A stone thrown from the top of a building is given an initial velocity of 20.0 m/s straight upward. Determine the time in seconds at which the stone reaches its maximum height. g =9.8 m /
Answer : Option B
Explaination / Solution:
Initial velocity u = 20.0 m/s
At maximum height it ll stop
So final velocity v = 0 m/s
Acceleration due to gravity g = 9.8 m/s2
Time taken to reach maximum height = t
We know
v = u + at
=>
[g is taken negative because it is in opposite direction of motion.]
Q2. Wavelength of the wave is the distance between two particles of the medium having a phase difference of
Answer : Option C
Explaination / Solution:
No Explaination.
Q3. A coil consists of 200 turns of wire having a total resistance of 2.0Ω. Each turn is a square of side 18cm, and a uniform magnetic field directed perpendicular to the plane of the coil is turned on. If the field changes linearly from 0 to 0.50 T in 0.80 s, Magnitude of the induced emf in the coil while the field is changing is
Answer : Option A
Explaination / Solution:
e=dϕdt
ϕ=NBA
e=200×0.50.8×(18×10−2)2=4.05V
Q4. Part of the electromagnetic spectrum to which 14.4 keV [energy of a particular transition in nucleus associated with a famous high resolution spectroscopic method (Mossbauer spectroscopy)] belongs is
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. If work function of a metal plate is negligible then the K.E.of the photoelectrons emitted when radiations of 1000 are incident on the metal surface is
Answer : Option A
Explaination / Solution:
No Explaination.
Q6. Pulse is specified by pulse height or the peak voltage, the pulse duration and pulse to pulse spacing. In pulse amplitude modulation (PAM) what changes with base band signal is
Answer : Option A
Explaination / Solution:
No Explaination.
Q7. A projectile is fired a velocity of 150 meters per second at an angle of 30 degrees with the horizontal. What is the magnitude of the vertical component of the velocity at the time the projectile is fired?
Answer : Option A
Explaination / Solution:
Initial velocity u = 150 m/s
Angle
Vertical component is given by
= 75 m/s
Q8. A solid metallic sphere has a charge + 3Q. Concentric with this sphere is a conducting spherical shell having charge –Q. The radius of the sphere is ‘a’ and that of spherical shell is ‘b’ (b>a). The electric field at a distance R (a
Answer : Option A
Explaination / Solution:
since we want to find electric field at point P at distance R from centre since at this point only the effect of that charge is taken which is at the surface of solid sphere so the electric field at point P at a distance R from centre is
since we want to find electric field at point P at distance R from centre since at this point only the effect of that charge is taken which is at the surface of solid sphere so the electric field at point P at a distance R from centre is
Q9.
A 14.5 kg mass, fastened to the end of a steel wire of unstretched length 1.0 m, is whirled in a vertical circle with an angular velocity of 2 rev/s at the bottom of the circle. The cross-sectional area of the wire is 0.065 . Calculate the elongation of the wire when the mass is at the lowest point of its path.
Answer : Option D
Explaination / Solution:
No Explaination.
Q10. A thermodynamic system undergoes a process in which its internal energy decreases by 500 J. If, at the same time, 220 J of work is done on the system, what is the energy transferred to or from it by heat?
Answer : Option B
Explaination / Solution:
ΔQ=ΔU+W=(−500)+(−220)=−720J
