1
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

A bat emitting an ultrasonic wave of frequency 4.5 $$\times$$ 104 Hz at speed of 6 m/s between two parallel walls. The two frequencies heard by the bat will be

A
4.67 $$\times$$ 104 Hz, 4.34 $$\times$$ 104 Hz
B
4.34 $$\times$$ 104 Hz, 4.67 $$\times$$ 104 Hz
C
4.5 $$\times$$ 104 Hz, 5.4 $$\times$$ 104 Hz
D
4.67 $$\times$$ 103 Hz, 4.34 $$\times$$ 103 Hz
2
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

A disc of moment of inertia 4 kg - m$$^2$$ revolving with 16 rad/s is placed on another disc of moment of inertia 8 kg - m$$^2$$ revolving 4 rad/s. The angular frequency of composite disc

A
4 rad/s
B
$$\frac{3}{16}$$ rad/s
C
8 rad/s
D
$$\frac{16}{3}$$ rad/s
3
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

An electric current $I$ enters and leaves a uniform circular wire of radius $r$ through diametrically opposite points. A charged particle $$q$$ moves along the axis of circular wire passes through its centre with speed $$v$$. The magnetic force on the particle when it passes through the centre has a magnitude

A
$$\frac{q v \mu_0 I}{2 \pi r}$$
B
$$q v \frac{\mu_0 I}{\pi r}$$
C
$$\frac{q v \mu_0 I}{r}$$
D
$$0$$
4
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

Television frequencies are of the order of 100 MHz, while radio frequencies are of the order of 1 MHz. Using these as typical frequencies, the ratio of the emf generated in a loop antenna by a television wave to that generated by a radio wave, if both have equal electric field intensities.

A
1
B
10
C
100
D
66.6
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