1
JEE Main 2022 (Online) 29th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

An alternating emf $$\mathrm{E}=440 \sin 100 \pi \mathrm{t}$$ is applied to a circuit containing an inductance of $$\frac{\sqrt{2}}{\pi} \mathrm{H}$$. If an a.c. ammeter is connected in the circuit, its reading will be :

A
4.4 A
B
1.55 A
C
2.2 A
D
3.11 A
2
JEE Main 2022 (Online) 29th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

A coil of inductance 1 H and resistance $$100 \,\Omega$$ is connected to a battery of 6 V. Determine approximately :

(a) The time elapsed before the current acquires half of its steady - state value.

(b) The energy stored in the magnetic field associated with the coil at an instant 15 ms after the circuit is switched on. (Given $$\ln 2=0.693, \mathrm{e}^{-3 / 2}=0.25$$)

A
t = 10 ms; U = 2 mJ
B
t = 10 ms; U = 1 mJ
C
t = 7 ms; U = 1 mJ
D
t = 7 ms; U = 2 mJ
3
JEE Main 2022 (Online) 29th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Match List - I with List - II :

List - I List - II
(a) UV rays (i) Diagnostic tool in medicine
(b) X-rays (ii) Water purification
(c) Microwave (iii) Communication, Radar
(d) Infrared wave (iv) Improving visibility in foggy days

Choose the correct answer from the options given below :

A
(a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
B
(a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
C
(a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
D
(a)-(iii), (b)-(i), (c)-(ii), (d)-(iv)
4
JEE Main 2022 (Online) 29th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The kinetic energy of emitted electron is E when the light incident on the metal has wavelength $$\lambda$$. To double the kinetic energy, the incident light must have wavelength:

A
$$\frac{\mathrm{hc}}{\mathrm{E} \lambda-\mathrm{hc}}$$
B
$$\frac{\mathrm{hc} \lambda}{\mathrm{E} \lambda+\mathrm{hc}}$$
C
$$\frac{\mathrm{h} \lambda}{\mathrm{E} \lambda+\mathrm{hc}}$$
D
$$\frac{\text { hc } \lambda}{\mathrm{E} \lambda-\mathrm{hc}}$$
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