Physics - Online Test
Q1. The temperature coefficient
of resistance of a wire is 0.00125 per °C. At 300 K, its resistance is 1 Ω. The
resistance of the wire will be 2 Ω at
Answer : Option D
Explaination / Solution:
Q2. Mp
denotes the mass of the proton and Mn denotes mass of a neutron. A
given nucleus of binding energy B, contains Z protons and N neutrons. The mass
M(N,Z) of the nucleus is given by(where c is the speed of light)
Answer : Option C
Explaination / Solution:
B = Δ mc2
B/c2 = Δm = NMn + ZMp − M(N,Z)
Q3. Two short bar magnets have
magnetic moments 1.20 Am2
and 1.00 Am2
respectively. They are kept on a horizontal table parallel to each other with
their north poles pointing towards the south. They have a common magnetic
equator and are separated by a distance of 20.0 cm. The value of the resultant
horizontal magnetic induction at the mid-point O of the line joining their
centers is (Horizontal components of Earth’s magnetic induction is 3.6 × 10-5 Wb m-2 )
Answer : Option C
Explaination / Solution:
Q4. Which one of the following represents forward bias diode?
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. An inductor 20 mH,
a capacitor 50 μF and a resistor 40 Ω are connected in
series across a source of emf v = 10 sin 340 t. The power loss in AC circuit is
Answer : Option C
Explaination / Solution:
Q6. Which one of them is used to produce a propagating electromagnetic wave?.
Answer : Option A
Explaination / Solution:
No Explaination.
Q7. A parallel plate capacitor
stores a charge Q at a voltage V. Suppose the area of the parallel plate
capacitor and the distance between the plates are each doubled then which is
the quantity that will change?
Answer : Option D
Explaination / Solution:
Q8. Photons of wavelength λ are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius R by a perpendicular magnetic field having magnitude B. The work function of the metal is
Answer : Option D
Explaination / Solution:
Centripetal
force (Fc.p) = Magnetic force (FB)
Q9. The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is
Answer : Option B
Explaination / Solution:
Q10. A radioactive nucleus (initial mass number A and atomic number Z) emits 2α and 2 positrons. The ratio of number of neutrons to that of proton in the final nucleus will be
Answer : Option B
Explaination / Solution:
In
finial nucleus,
Number
of neutons:
NA
= A – 8 – (Z – 6) = A – Z – 2
Number
of protons:
Np
= Z – 6
Nn
/ Np = [ A – Z – 2 ] / [Z – 6]
