A metallic circular loop is placed with its plane perpendicular to a uniform magnetic field of 0.3 T . If the radius of the loop decreases at a constant rate of $2 \mathrm{~mm} \mathrm{~s}^{-1}$, what will be the induced emf in the loop, when the radius of the loop becomes 5 cm .
$1.5 \times 10^{-6} V$
$0.75 \times 10^{-6} V$
$1.84 \times 10^{-6} V$
$1.89 \times 10^{-4} V$
What is the minimum wavelength of radiation required to detect a p-n junction diode made of a semiconductor having band gap 3.3 eV .
[Planck's constant $h=6.6 \times 10^{34} \mathrm{~J} . \mathrm{s}$ ]
$3300^{\circ} \mathrm{A}$
$4800^{\circ} \mathrm{A}$
$3750^{\circ} \mathrm{A}$
$7500^{\circ} \mathrm{A}$
A galvanometer of resistance $50 \Omega$ is having 30 divisions and a current sensitivity $10 \mathrm{~mA} /$ div. What should be the shunt resistance so that it can be converted into an ammeter of range 10 A ?
$0.76 \Omega$
$2.5 \Omega$
$1.55 \Omega$
$3.1 \Omega$
A block of mass 1.5 kg moves along the floor of a hall with a speed of $5 \mathrm{~ms}^{-1}$. It strikes an uncompressed spring and compresses it till the block becomes motionless. If the force constant of the spring is $10000 \mathrm{Nm}^{-1}$ and the spring is compressed by 5 cm , calculate the effective force of kinetic friction.
125 N
18.7 N
0
16.4 N
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