Practice MCQ Questions and answers on Physics-GK

61

Find the power of a convex lens if the image formed is at a distance of 25 cm from the lens when the object is placed on the other side of the lens at 12 cm from the optical centre?

A) -4.33 diopters B) 12.33 diopters C) -12.33 diopters D) 4.33 diopters

Discuss

Answer & Solution

Answer: Option B

No explanation is given for this question. Let's Discuss on Board

62

Find the power of a convex lens if the image formed is at a distance of 16 cm from the lens when the object is placed on the other side of the lens at 20 cm from the optical centre?

A) -3.75 diopters B) -11.25 diopters C) 3.75 diopters D) 11.25 diopters

Discuss

Answer & Solution

Answer: Option D

No explanation is given for this question. Let's Discuss on Board

63

A colour-blind person cannot

A) See distant objects B) See black colour C) Distinguish between certain colours D) Have persistence of vision

Discuss

Answer & Solution

Answer: Option C

Solution:

A colour-blind person cannot distinguish between certain colours.

64

Magnifying Glass is basically a

A) Plano-concave lens B) Concave lens C) Convex lens D) Cylindrical lens

Discuss

Answer & Solution

Answer: Option C

Solution:

A magnifying glass (called a hand lens in laboratory contexts) is a convex lens that is used to produce a magnified image of an object.

65

A microscope used in pathological laboratories forms

A) Magnified, virtual, erect image B) Diminished, real and erect image C) Magnified, virtual and inverted image D) Diminished, virtual and erect image

Discuss

Answer & Solution

Answer: Option C

Solution:

A microscope is an instrument that produces a clear magnified image of an object viewed through it. A basic microscope is made up of two converging lenses. The first lens creates a real image which serves as the object for the second lens, and the image created by the second lens is the one a viewer sees. The final image is virtual and is inverted compared to the original object.

66

Which of the following characteristics of light remains unchanged when light travels from vaccum enters water?

A) Speed B) Amplitude C) Frequency D) Wavelength

Discuss

Answer & Solution

Answer: Option C

Solution:

Frequency of light remains unchanged when light travels from vaccum enters water.

67

To resolve an object in an electron microscope,

A) The wavelength of the electrons must be close to the diameter of the object B) The wavelength of the electrons must be greater than the diameter of the object. C) Both A & B D) None of the above

Discuss

Answer & Solution

Answer: Option A

Solution:

To resolve an object in an electron microscope, the wavelength of the electrons must be close to the diameter of the object.

68

Which of the following is an example of continous emission spectrum?

A) Spectrum of an oil frame B) Spectrum of a water C) Both D) None

Discuss

Answer & Solution

Answer: Option A

Solution:

Spectrum of an oil frame is an example for continuous emission spectrum.

69

The atmospheric layer reflecting radio waves is called

A) Ozonosphere B) Ionosphere C) Stratosphere D) Mesosphere

Discuss

Answer & Solution

Answer: Option B

Solution:

The low-frequency end of the window is limited by signals being reflected by the ionosphere back into space, while the upper limit is caused by absorption of the radio waves by water vapour and carbon dioxide in the atmosphere.

70

For a ray of light to suffer total internal reflection it has to pass from :

A) Glass to water B) Water to glass C) Air to water D) Air to glass

Discuss

Answer & Solution

Answer: Option C

Solution:

Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. This can only occur where light travels from a medium with a higher [n1=higher refractive index] to one with a lower refractive index [n2=lower refractive index]. Total internal reflection can be seen at the air-water boundary.