1
JEE Main 2021 (Online) 24th February Morning Slot
Numerical
+4
-1
A common transistor radio set requires 12 V (D.C.) for its operation. The D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V (A.C.) on standard domestic A.C. supply. The number of turns of secondary coil are 24, then the number of turns of primary are ___________.
2
JEE Main 2021 (Online) 24th February Morning Slot
Numerical
+4
-1
A resonance circuit having inductance and resistance 2 $$\times$$ 10$$-$$4 H and 6.28$$\Omega$$ respectively oscillates at 10 MHz frequency. The value of quality factor of this resonator is ___________. [$$\pi$$ = 3.14]
3
JEE Main 2020 (Online) 6th September Evening Slot
Numerical
+4
-0
In a series LR circuit, power of 400W is dissipated from a source of 250 V, 50 Hz. The power factor of the circuit is 0.8. In order to bring the power factor to unity, a capacitor of value C is added in series to the L and R. Taking the value of C as $$\left( {{n \over {3\pi }}} \right)$$ $$\mu$$F, then value of n is __________.
4
JEE Main 2020 (Online) 6th September Morning Slot
Numerical
+4
-0
Suppose that intensity of a laser is $${{315} \over \pi }$$ W/m2.
The rms electric field, in units of V/m associated with this source is close to the nearest integer is __________.

$$\in$$0 = 8.86 × 10–12 C2 Nm–2; c = 3 × 108 ms–1)
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