1
VITEEE 2021
MCQ (Single Correct Answer)
+1
-0

The magnetic field at a point on the axis of a long solenoid having 5 turns per $$\mathrm{cm}$$ length when a current of $$0.8 \mathrm{~A}$$ flows through it is

A
$$5.024 \times 10^{-8} \mathrm{~Wb} / \mathrm{m}^2$$
B
$$6.024 \times 10^{-8} \mathrm{~Wb} / \mathrm{m}^2$$
C
$$7.024 \times 10^{-8} \mathrm{~Wb} / \mathrm{m}^2$$
D
$$8.024 \times 10^{-8} \mathrm{~Wb} / \mathrm{m}^2$$
2
VITEEE 2021
MCQ (Single Correct Answer)
+1
-0

An object is $$8 \mathrm{~cm}$$ high. It is desired to form a real image $$4 \mathrm{~cm}$$ high at $$60 \mathrm{~cm}$$ from the mirror. The type of mirror needed with the focal length is

A
convex mirror with focal length $$f=40 \mathrm{~cm}$$
B
convex mirror with focal length $$f=20 \mathrm{~cm}$$
C
concave mirror with focal length $$f=-40 \mathrm{~cm}$$
D
concave mirror with focal length $$f=-20 \mathrm{~cm}$$
3
VITEEE 2021
MCQ (Single Correct Answer)
+1
-0

When an object is placed $$40 \mathrm{~cm}$$ from a diverging lens, its virtual image is formed $$20 \mathrm{~cm}$$ from the lens. The focal length and power of lens are

A
$$f=-20 \mathrm{~cm}, P=-5 \mathrm{D}$$
B
$$f=-40 \mathrm{~cm}, P=-5 \mathrm{D}$$
C
$$f=-40 \mathrm{~cm}, P=-2.5 \mathrm{D}$$
D
$$f=-20 \mathrm{~cm}, P=-2.5 \mathrm{D}$$
4
VITEEE 2021
MCQ (Single Correct Answer)
+1
-0

Polonium has a half-life of 140 days. If we take $$20 \mathrm{~g}$$ of polonium initially then the amount of it that remains after 280 days is

A
2.5 g
B
5 g
C
10 g
D
15 g
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