2009 - JAMB Physics Past Questions and Answers - page 5
41
It is observed that water will wet a clean glass because the
A
cohesion of water to glass is stronger than the cohesion of water molecules
B
adhesion of water molecules is weaker than the cohesion of water to glass
C
cohesion of water to glass is weaker than the cohesion of water molecules
D
adhesion of water molecules is stronger than the cohesion of water molecules
correct option: d
When the adhesion of liquid molecules to the glass is more than the cohesion of the liquid, the liquid will wet glass.
Users' Answers & Comments42
A man standing 2 m from a charcoal fire is warmed mainly by
A
convection
B
radiation
C
refraction
D
conduction
correct option: b
Radiation is the method of heat transfer without any unit ervening venue
Users' Answers & Comments43
Metal cables are used as telephone wires because
A
they are cheap
B
they are sourced locally
C
the speed of sound in them is very low
D
the speed of sound in them is very high
correct option: d
The speed of sound is highest in solid, being about 500, units in steel rod
Users' Answers & Comments44
Musical instruments playing the same note can be distinguished from one another owing to the differences in their
A
quality
B
pitch
C
intensity
D
loudness
correct option: a
The quality of a note is a characteristic that distinguishes it from note of the same frequency played by another musical instrument.
Users' Answers & Comments45
I. Moon.
II. Sun.
III.street light.
IV. stars.
Which of these above is a natural source of light?
II. Sun.
III.street light.
IV. stars.
Which of these above is a natural source of light?
A
II, III, and IV only
B
I, II and III only
C
III and IV only
D
II and IV only
46
An object is placed 5 cm from the pole of a concave mirror. if the focal length of the mirror is 10 cm. what is the image distance?
A
10 cm in front of the mirror.
B
5 cm in front of the mirror
C
10 cm behind the mirror
D
5 cm behind the mirror
correct option: c
u = 5 cm , f = 10 cm, v = ?
(1)/v + (1)/u = (1)/f
(1)/v + (1)/5 = (1)/10
= (1)/v = (1)/10 = (1)/5 = (1 - 2)/10 = (1)/10
∴ v = - 10 cm
∴ The image is 10 cm behind the mirror
Users' Answers & Comments(1)/v + (1)/u = (1)/f
(1)/v + (1)/5 = (1)/10
= (1)/v = (1)/10 = (1)/5 = (1 - 2)/10 = (1)/10
∴ v = - 10 cm
∴ The image is 10 cm behind the mirror
47
Calculate the position of an object placed in front of a convex mirror having focal length of 12 cm such that an image is formed 6 cm away from the mirror
A
4. 0 cm
B
3. 0 cm
C
12.0 cm
D
9.0 cm
correct option: c
f = -12 cm, v = - 6 cm
(1)/v + (1)/u =(1)/f
(1)/-6 + (1)/u = (1)/-12
(1)/u = (1)/-12 + (1)/6 = (1 + 2)/12 = (1)/12
∴ u = 12 cm
Users' Answers & Comments(1)/v + (1)/u =(1)/f
(1)/-6 + (1)/u = (1)/-12
(1)/u = (1)/-12 + (1)/6 = (1 + 2)/12 = (1)/12
∴ u = 12 cm
48
If the refractive index of crown glass is 1.51, its critical angel is.
A
48.6°
B
22.5°
C
41.5°
D
45.0°
correct option: c
Sin c = (1)/n
= (1)/1.51 = 0.6622
∴ c = sin +0.6622 = 41.47
Users' Answers & Comments= (1)/1.51 = 0.6622
∴ c = sin +0.6622 = 41.47
49
When light passes through two media x and y of refraction indices 1.51 and 1.33 respectively, the speed of light in
A
x is same as in y
B
x and y is same as in vacuum
C
x is higher than in y
D
y is higher than in x
correct option: d
Since 1.51, the refractive index of X is greater than 1.33, the refractive index of y, the speed of light in y is higher than that in X
Users' Answers & Comments