$A$ circular coil of mean radius $7 \, cm$ and having $4000$ turns is rotated at the rate of $1800$ revolutions per minute in the earth's magnetic field $(B = 0.5 \, \text{gauss})$. The maximum $e.m.f.$ induced in the coil will be .... $V$.

$A$ rectangular coil of $300$ turns has an average area of $25\;cm \times 10\;cm.$ The coil rotates with a speed of $50\;cps$ in a uniform magnetic field of strength $4 \times 10^{-2}\;T$ about an axis perpendicular to the field. The peak value of the induced $e.m.f.$ is (in volt): (in $\pi$)

When a wire loop is rotated in a magnetic field,the direction of induced $emf$ changes in every

$A$ circular coil of area $0.01 \ m^2$ and $40$ turns is rotated about its vertical diameter with an angular speed of $50 \ rad \ s^{-1}$ in a uniform horizontal magnetic field of $0.05 \ T$. If the average power loss due to Joule heating is $25 \ mW$,then the closed loop resistance of the coil is: (in $Omega$)

The number of turns in the coil of an $AC$ generator are $50$ and its cross-sectional area is $2.5 \ m^2$. This coil is revolving in a uniform magnetic field of strength $0.3 \ T$ with a uniform angular velocity of $60 \ rad \ s^{-1}$. The resistance of the circuit comprising the coil is $500 \ \Omega$. The maximum induced $emf$ and maximum current produced in the generator are:

$A$ ring of resistance $10 \ \Omega$,radius $10 \ cm$ and $100$ turns is rotated at a rate of $100$ revolutions per second about its diameter perpendicular to a uniform magnetic field of induction $10 \ mT$. The amplitude of the current in the loop will be nearly $....... \ A$. (Take: $\pi^2 = 10$)