Physics 2018 | Study Mode

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Question 21
A
splits into three components after rainfall
B
is dispersed by glass prisms
C
splits into its constituent colours before rainfall
D
is dispersed into its constituent colours after rainfall
Explanation

A rainbow is caused by the dispersion of sunlight by tiny water droplets present in the atmosphere, which can be seen after the rain.


Correct option: D
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Question 22
A
converging meniscus
B
plano-convex
C
diverging meniscus
D
bi-convex
Explanation

The diagram is that of a plano-convex lens; a type of converging lens.


Correct option: B
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Question 23
A
30
B
45
C
60
D
90
Explanation

Formula for number of images = \(\frac{360}{n} - 1\)

where n is the angle of inclination.

Given the number of images = 11, we have

\(\frac{360}{n} - 1 = 11\)

\(\frac{360}{n} = 12\)

\(n = \frac{360}{12} =30\)


Correct option: A
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Question 24
A
frequency
B
tension in a vibrating string
C
mass of a vibrating string
D
amplitude of sound wave
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: D
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Question 25
A
electroscope
B
electrophorus
C
capacitor
D
cell
Explanation

Most capacitors contain at least two electrical conductors often in the form of metallic plates or surfaces separated by a dielectric medium.


Correct option: C
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Question 26
A
a.c. generator
B
a.c. motor
C
d.c. generator
D
d.c. motor
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: C
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Question 27
A
1358mm
B
957mm
C
760mm
D
638mm
Explanation

Let \(h_{Q}\) and \(\rho_{Q}\) be the least length and the density of \(Q_{1}\)

while \(h\) and \(\rho\) are the length and density of mercury respectively.

\(h\times \rho \times g = h_{Q} \times \rho_{Q} \times g\)

\(76cm \times 13.6 \times 10 = h_{Q} \times 16.2 \times 10\)

\(h_{Q} = \frac{76\times13.6\times10}{16.2\times10}\)

\(h_{Q} = \frac{10336}{162}\)

\(h_{Q} \approxeq 63.8cm = 638mm\)


Correct option: D
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Question 28
A
10.0N
B
20.0N
C
40.0N
D
50.0N
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: C
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Question 29
A
between the focus and the lens
B
at the focus
C
between the focal length and twice the focal length
D
beyond twice the focal length
Explanation

When the object is placed between the optical centre of the lens and the focal length, the image formed is virtual, erect and magnified.


Correct option: A
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Question 30
A
A and E
B
B and D
C
C and F
D
D and H
Explanation

Explanation not provided, please join discuss, your contributions are welcomed


Correct option: D

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