MHT CET 2021 22th September Evening Shift | Alternating Current Question 113 | Physics

A parallel plate capacitor having plates of radius 6 cm has capacitance 100 pF. It is connected to 230 V a.c. supply with angular frequency 300 rad/s. The r.m.s. value of current is

$$6.9\times10^{-6}$$ A

$$2.3\times10^{-5}$$ A

$$6.9\times10^{-5}$$ A

$$6.9\times10^{-7}$$ A

MHT CET 2021 22th September Evening Shift

MCQ (Single Correct Answer)

-0

A step down transformer has turns ratio $$20: 1$$. If $$8 \mathrm{~V}$$ is applied across $$0.4 \mathrm{~ohm}$$ secondary then the primary current will be

2 A

1 A

0.5 A

4 A

MHT CET 2021 22th September Morning Shift

MCQ (Single Correct Answer)

-0

An a.c. source of angular frequency '$$\omega$$' is fed across a resistor '$$R$$' and a capacitor '$$C$$' in series. The current registered is I. If now the frequency of source is changed to $$\frac{\omega}{3}$$ (but maintaining the same voltage), the current in the circuit is found to be halved. The ratio of reactance to resistance at the original frequency '$$\omega$$' will be

$$\sqrt{\frac{2}{5}}$$

$$\sqrt{\frac{1}{5}}$$

$$\sqrt{\frac{4}{5}}$$

$$\sqrt{\frac{3}{5}}$$

MHT CET 2021 22th September Morning Shift

MCQ (Single Correct Answer)

-0

In an a.c. circuit, a resistance R = 40 $$\Omega$$ and an inductance 'L' are connected in series. If the phase angle between voltage and current is 45$$^\circ$$, then the value of the inductive reactance is (tan 45$$^\circ$$ = 1)

50$$\Omega$$

40$$\Omega$$

10$$\Omega$$

20$$\Omega$$

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