1
JEE Main 2024 (Online) 30th January Evening Shift
+4
-1

An alternating voltage $$V(t)=220 \sin 100 \pi t$$ volt is applied to a purely resistive load of $$50 \Omega$$. The time taken for the current to rise from half of the peak value to the peak value is:

A
7.2 ms
B
3.3 ms
C
5 ms
D
2.2 ms
2
JEE Main 2024 (Online) 30th January Morning Shift
+4
-1

Primary coil of a transformer is connected to $$220 \mathrm{~V}$$ ac. Primary and secondary turns of the transforms are 100 and 10 respectively. Secondary coil of transformer is connected to two series resistances shown in figure. The output voltage $$\left(V_0\right)$$ is :

A
7 V
B
44 V
C
22 V
D
15 V
3
JEE Main 2024 (Online) 30th January Morning Shift
+4
-1

A series L.R circuit connected with an ac source $$E=(25 \sin 1000 t) V$$ has a power factor of $$\frac{1}{\sqrt{2}}$$. If the source of emf is changed to $$\mathrm{E}=(20 \sin 2000 \mathrm{t}) \mathrm{V}$$, the new power factor of the circuit will be :

A
$$\frac{1}{\sqrt{3}}$$
B
$$\frac{1}{\sqrt{2}}$$
C
$$\frac{1}{\sqrt{5}}$$
D
$$\frac{1}{\sqrt{7}}$$
4
JEE Main 2024 (Online) 29th January Evening Shift
+4
-1

In an a.c. circuit, voltage and current are given by:

$$V=100 \sin (100 t) V$$ and $$I=100 \sin \left(100 t+\frac{\pi}{3}\right) \mathrm{mA}$$ respectively.

The average power dissipated in one cycle is:

A
5 W
B
25 W
C
2.5 W
D
10 W
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