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Light Test - 30

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SHARING IS CARING

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Weekly Quiz Competition

Question 1
1 / -0

A plane mirror is approaching you at a speed of $$10$$ cm/s you can see your image in it. At what speed will your image approach you?

A
$$10$$ cm/s

B
$$5$$ cm/s

C
$$20$$ cm/s

D
$$15$$ cm/s

Solution

Suppose at any instant, plane mirror lies at a distance $$x$$ from the object. The image will be formed behind the mirror at the same distance $$x$$.
When the mirror shifts towards the object by distance $$'y'$$ the image shifts $$=x+y-(x-y)=2y$$
So speed of image $$=2\times $$speed of mirror
hence $$=2\times 10 =20 / m/s$$
Question 2
1 / -0

Image formed by a convex spherical mirror is:

A
virtual

B
real

C
enlarged

D
inverted

Solution

A convex spherical mirror always produces a virtual, and diminished image of an object.
Question 3
1 / -0

A plane mirror is placed vertically facing due north. An arrow pointing north-east is kept in front of the mirror. In which direction will the arrow point in this image ?

A
north-east

B
south-east

C
south-west

D
north-west

Solution

The arrow pointing north-east will have be resultant of two directions-north and east. The horizontal component of arrow facing east will be same on reflection. But the vertical component of arrow facing the plane mirror will be reflected and be reversed. Thus, the image will have an arrow resultant of south-east direction.
Question 4
1 / -0

Boojho and Paheli were given one mirror each by their teacher. Boojho found his image to be erect and of the same size whereas Paheli found her image erect and smaller in size. This means that the mirrors of Boojho and Paheli are, respectively.

A
Plane mirror and concave mirror.

B
Concave mirror and convex mirror.

C
Plane mirror and convex mirror.

D
Convex mirror and plane mirror.

Solution

When the image is erect and of same size as object then it is a plane mirror so Boojho has plane mirror
When the image is erect and of small size than object then it is a convex mirror so Paheli has a convex mirror
Question 5
1 / -0

Four students $$A, B, C$$ and $$D$$ looked through pipes of different shapes to see a candle flame as shown in Fig.
Who will be able to see the candle flame clearly?

A
$$A$$

B
$$B$$

C
$$C$$

D
$$D$$

Solution

The correct answer is option (d) $$D$$. The tube is straight in fig $$D$$. Therefore, candle flame will be visible clearly to us.
Question 6
1 / -0

Which of the following can be used to form a real image?

A
Concave mirror only.

B
Plane mirror only.

C
Convex mirror only.

D
Both concave and convex mirrors.

Solution

The correct answer is option (b), plane mirror. Plane mirror always forms image of equal size and erected image.
Question 7
1 / -0

The image formed by a plane mirror is:

A
Virtual and inverted

B
Virtual and erect

C
Real and Inverted

D
Real and erect

Solution

The image formed by a plane mirror is erect. It is virtual and is of the same size as the object. The image is at the same distance behind the mirror as the object is in front of it.
Question 8
1 / -0

A convex mirror is used

A
as a shaving mirror

B
as a head by a dentist.

C
as a rear view mirror by a driver

D
as a reflector in torch.

Solution

A convex mirror is used as a rearview mirror because it gives an upright image and provides a wider field of view.
Question 9
1 / -0

Focal length of plane mirror is

A
at infinity

B
zero

C
negative

D
none of these

Solution

A plane mirror is a flat reflecting surface. Thus, in the case of a plane mirror, when the parallel rays of light strike the mirror they get reflected back parallel to each other. So, they never meet or we can say they meet at infinity. So, the focal length of the plane mirror is Infinity.
Question 10
1 / -0

The focal length of a mirror is +60 cm. Which kind of mirror it is?

A
Concave mirror

B
Parabolic mirror

C
Plain mirror

D
Convex mirror

Solution

Convex mirror has positive focal length.

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Re-Attempt Weekly Quiz Competition

Light Test - 30

Result

Light Test - 30

Score

-

Rank

-

SHARING IS CARING

Question 1

$$10$$ cm/s

$$5$$ cm/s

$$20$$ cm/s

$$15$$ cm/s

Solution

Question 2

virtual

real

enlarged

inverted

Solution

Question 3

north-east

south-east

south-west

north-west

Solution

Question 4

Plane mirror and concave mirror.

Concave mirror and convex mirror.

Plane mirror and convex mirror.

Convex mirror and plane mirror.

Solution

Question 5

$$A$$

$$B$$

$$C$$

$$D$$

Solution

Question 6

Concave mirror only.

Plane mirror only.

Convex mirror only.

Both concave and convex mirrors.

Solution

Question 7

Virtual and inverted

Virtual and erect

Real and Inverted

Real and erect

Solution

Question 8

as a shaving mirror

as a head by a dentist.

as a rear view mirror by a driver

as a reflector in torch.

Solution

Question 9

at infinity

zero

negative

none of these

Solution

Question 10

Concave mirror

Parabolic mirror

Plain mirror

Convex mirror

Solution

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