JAMB Physics Past Questions & Answers - Page 329

1,641.

The most suitable type of mirror used for the construction of the search light is the?

A.

concave mirror

B.

convex mirror

C.

spherical mirror

D.

parabolic mirror

Correct answer is D

In optics, parabolic mirrors are used to gather light in reflecting telescopes and solar furnaces, and project a beam of light in flashlights, searchlights, stage spotlights, and car headlights.

1,642.

An object is placed in front of two plane mirrors inclined at an angle of 0o. If the total number of images formed is 7, Find the value of \(\theta\)

A.

30o

B.

45o

C.

51o

D.

90o

Correct answer is B

Number of image = \(\frac{360}{\theta}\) -1

7 = \(\frac{360}{\theta}\) -1

thus,\(\theta\) = 45o

1,643.

An object 0 lies at a distance m in front of concave mirror of focal length f. If m < f, then the final image obtained will be

A.

virtual and diminished

B.

magnified and erect

C.

real and inverted

D.

diminished and erect

Correct answer is B

In a concave mirror, when the object distance is less than the focal length, we have an image which is:

- Virtual

- Erect and 

- Magnified.

1,645.

A steel wire of length 0.50m is stretched between two fixed points and its fundamental frequency is 200Hz. The speed of the wave in the wire is

A.

100ms-1

B.

120ms-1

C.

200ms-1

D.

250ms-1

Correct answer is C

In strings, \(\lambda\) = 2L

V = F\(\lambda\)

= 200 x 2 x 0.5

= 200ms-1