Light Test

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Light Test - 11

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Weekly Quiz Competition

Question 1
1 / -0

In which mirror is the image formed always virtual?

a. Plane mirror
b. Convex mirror
c. Concave mirror

A
Only a

B
Only b

C
Only c

D
a and b

E
#

Solution

Both a plane mirrors and a convex mirror, always form a virtual image.The image formed by a plane mirror appears to be behind the plane in which the mirror lies, thus, the image is virtual. Convex mirror is known as a diverging mirror as in this mirror, light diverges when it strikes on its reflecting surface.These rays seem to meet behind the mirror, thus, the image formed by it is virtual.
Question 2
1 / -0

When an object is kept between the focus and the pole, the image formed by a concave mirror is _________.

A
real, inverted and of the same size

B
real, inverted and smaller in size

C
virtual, erect and magnified

D
real, inverted and magnified

E
#

Solution

When the object is kept between the focus and the pole, the image formed by a concave mirror is virtual, erect and magnified.
Question 3
1 / -0

For maximum utility, the bulb of a car's headlight should be kept

A
beyond the centre of curvature

B
at focus

C
between the focus and the pole

D
between the centre of curvature and the focus

E
#

Solution

In a car's headlight, the bulb is placed at the focus so that a highly enlarged image is obtained at the infinity.
Question 4
1 / -0

What are the characteristics of the image formed at the retina?

A
Real, smaller and erect

B
Real, magnified and erect

C
Smaller, real and upside down

D
Magnified, real and upside down

E
#

Solution

The characteristics of the image formed at the retina are that the image formed is smaller, real and upside down. It is further processed in the brain.
Question 5
1 / -0

When a mirror is rotated through an angle of 30 degrees, with what angle would the reflected ray turn?

A
90 degrees

B
15 degrees

C
30 degrees

D
60 degrees

E
#

Solution

When a mirror is rotated through an angle of 30 degrees, the reflected ray would turn by two times the angle of rotation of the mirror i.e. 30x2= 60 degrees.
Question 6
1 / -0

In a plane mirror, if an object moves by a distance 'x', then what is the distance moved by the image with respect to the object?

A
2x

B
x

C
x/2

D
x²

E
#

Solution

In case of a plane mirror, the distance of the image is always equal to the distance of the object from the mirror.If an object moves a distance 'x' towards the mirror, then the distance moved by the image towards the mirror is 'x'. Hence, the relative separation of the image and the object decreases by 2x or it can be said that the distance moved by the image with respect to the object is 2x.If an object moves a distance 'x' away the mirror, then the distance moved by the image away from the mirror is 'x'. Hence, the relative separation of the image and the object increases by 2x or it can be said that the distance moved by the image with respect to the object is 2x.
Question 7
1 / -0

In a concave mirror, all the rays parallel to the principal axis converge at which point?

A
Centre of curvature

B
Focus

C
Pole

D
Between the pole and the focus

E
#

Solution

In a concave mirror, all the rays parallel to the principal axis converge at the focus.
Question 8
1 / -0

A ray passing through the centre of curvature (C), after hitting the concave mirror, ___________ .

A
goes back through the focus

B
goes back parallel to the principal axis

C
goes back along the same path through C

D
gets reflected by mirror at 45 degree

E
#

Solution

A ray passing through centre of curvature (C), after hitting the mirror, goes back along the same path through C because, as the ray of light passes through the centre of curvature of a concave mirror, it strikes the mirror along the normal i.e. it incidences on to the mirror at 0°. Hence, the incident ray coincides with the normal and when the incident ray coincides with the normal, it retraces its path.
Question 9
1 / -0

A concave mirror is used everywhere except in a

A
dentist mirror

B
shaving mirror

C
torch

D
rear view mirror

E
#

Solution

A convex mirror is used in the rear view mirror because it forms an erect, virtual, and diminished image which allows the driver to view a large area in a small mirror.
Question 10
1 / -0

Choose the most appropriate option:

In a convex lens, if the object is at an infinity, the image formed is

a. obtained at focus
b. virtual
c. highly diminished

A
a and b

B
b

C
c and d

D
a and c

E
#

Solution

In a convex lens, if the object is at infinity, the image is formed at the focus (F₂) and is highly diminished.
Question 11
1 / -0

When a convex lens is used as a magnifying glass, the object looks magnified if ________.

A
the object is at 2F1

B
the object is between F and O

C
the object is beyond 2F1

D
the object is at infinity

E
#

Solution

When the object is placed between F and O, a highly enlarged and an erect image is formed on the same side as that of object. Thus, the object looks magnified, if kept at this position.
Question 12
1 / -0

Which colour is absent in the spectrum formed by a cut diamond?

A
Violet

B
Purple

C
Blue

D
Indigo

E
#

Solution

Purple colour is not present in the spectrum.
Question 13
1 / -0

Where is the image formed, if the object is kept anywhere between the infinity and 2F1 of a concave lens?

A
At 2F1

B
At F1

C
Between F1 and the optical centre

D
Beyond the lens

E
#

Solution

If the object is kept anywhere between the infinity and 2F1, the image formed is between F1 and the optical centre.
Question 14
1 / -0

The outer curved surface of a spoon acts as a ___________.

A
concave mirror

B
convex mirror

C
plane mirror

D
convex lens

E
#

Solution

The outer curved surface of a spoon acts as a convex mirror.
Question 15
1 / -0

Which of the following equation gives the correct relation between the focus (F) and the centre of curvature (C)?

A
F = 2C

B
F = 1/2 C

C
F = C

D
C = 1/2 F

E
#

Solution

F is related to C by F = 1/2 C, it means that the focus is half the length of the centre of curvature (C) from the pole.

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Light Test - 11

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Light Test - 11

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SHARING IS CARING

Question 1

Only a

Only b

Only c

a and b

#

Solution

Question 2

real, inverted and of the same size

real, inverted and smaller in size

virtual, erect and magnified

real, inverted and magnified

#

Solution

Question 3

beyond the centre of curvature

at focus

between the focus and the pole

between the centre of curvature and the focus

#

Solution

Question 4

Real, smaller and erect

Real, magnified and erect

Smaller, real and upside down

Magnified, real and upside down

#

Solution

Question 5

90 degrees

15 degrees

30 degrees

60 degrees

#

Solution

Question 6

2x

x

x/2

x2

#

Solution

Question 7

Centre of curvature

Focus

Pole

Between the pole and the focus

#

Solution

Question 8

goes back through the focus

goes back parallel to the principal axis

goes back along the same path through C

gets reflected by mirror at 45 degree

#

Solution

Question 9

dentist mirror

shaving mirror

torch

rear view mirror

#

Solution

Question 10

a and b

b

c and d

a and c

#

Solution

Question 11

the object is at 2F1

x²