Physics Question and Answers for Students
Q 1:- What are
you doing with Vernier Callipers?
Answer:- I am
going to find volume of a solid cylinder and capacity of a tube with Vernier
Callipers.
Q 2:- Why it is
called Vernier Callipers?
Answer:- It was
invented by Piere Vernier, that’s why it is called Vernier Callipers.
Q 3:- How many
Scales are there in a Vernier Callipers?
Answer:- There
are two scales in Vernier Callipers:
i)
Main
Scale
ii)
Vernier
Scale
Q 4:- What are
the units of these scales?
Answer:- The
unit of “main scale” is mm while vernier scale has no unit.
Q 5:- What is
the relation between main scale and vernier scale?
Answer:- 10
divisions of vernier scale = 9 mm of main scale.
OR
20 divisions of
vernier scale = 39 mm of main scale.
Q 6:- What is
the use of lower jaws of vernier calipers?
Answer:- Lower
jaws are used to find thickness, length, external diameter etc.
Q 7:- What is
the use of upper jaws?
Answer:- Upper
jaws are used to find internal diameter, internal width etc.
Q 8:- What is
the use of the depth gauge (sliding strip) of vernier callipers?
Answer:- it is
used to find the depth of a tube or cylinder.
Q 9:- What do
you mean by least count?
Answer:- The
smallest measurement that can be made by an instrument is called its least
count.
Q 10:- What is
the least count of a vernier callipers?
Answer:- The
least count of a vernier calipers is 0.1 mm for 10 divisions vernier scale and
0.05 mm for 20 divisions vernier scale.
It can be found by formula
L. C. = 
Q 11:- What do
you mean by “zero error”.
Answer: If zero
of main scale does not coincide with the zero of vernier scale then there is
error in the instrument. This error is called “zero error”
Q 12:- Under
what conditions zero error be positive and negative?
Answer: - Zero
error will be positive if “zero” of vernier scale is on the right side of the “zero”
of main scale and negative when “zero” of vernier scale is on the left side of
the “zero” of main scale.
Q 13:- is “zero error” added or subtracted from a
reading?
Answer: “zero
error” is always subtracted from a reading to obtain accurate result.
Q 14:- Why
vernier calliper is given preference on an ordinary foot scale.
Answers: Least
count of vernier calipers is smaller than the ordinary foot scale so its
reading is more accurate.
Q 15:- What do
you mean by volume?
Answer: Space
occupied by a body is called its volume. Its unit is m3 or cm3
or mm3.
Q 16:- What do
you mean by diameter?
Answer: The
length of the line which join opposite sides of a circle and passes through the
center of the circle is called its “diameter”. Its unit is m, cm or mm.
Q 17:- What do
you mean by radius?
Answer:- Half
of the diameter is called “radius” OR Length of the line
which join center of a circle and a point on circumference of the circle is
called “radius” of the circle.
Q 18:- What do
you mean by “capacity of a tube”?
Answer:- The
inner volume of a tube is called its capacity. Its unit is m3, cm3
or mm3.
Q 19: What are
you doing with micrometer screw gauge?
Answer: I am
going to find
(i)
Volume
of solid sphere
(ii)
Area
of cross-section of a piece of wire with micrometer screw gauge.
Q 20:- How many
meters in one micrometer?
Answer: - 1μm =
10– 6 and 1 m = 106 μm
Q
21:- How many scales are there in a
micrometer screw gauge?
Answer:
There are two scales in a
micrometer screw gauge.
(i) Main
Scale
(ii) Circular
Scale
Q
22:- What are the units of
main scale and circular scale?
Answer:
The unit of main scale is “mm”
while circular scale has no unit.
Q
23:- What is the least count
of micrometer screw gauge?
Answer:
The least count of micrometer
screw gauge is 0.01mm or 0.001cm
Q
24:- What is the formula of
finding least count?
Answer:
Least
count = 
e.g. for 50
divisions circular scale micrometer.
L.C. = 
= 0.01mm = 0.001cm
= 0.01mm = 0.001cm
For
100 divisions circular scale micrometer.
L.C. = 
= 0.01mm = 0.001cm
= 0.01mm = 0.001cm
Q
25:- What do you mean by
“pitch” of the screw?
Answer:
Distance between two nearest
threads of a screw is called its “pitch”.
Q
26:- What do you mean by
“Zero Error”?
Answer:
If “Zero” of main scale does not
coincides with the “zero” of circular scale then these is error in the
instrument. This error is called “Zero Error”.
Q
27:- Under what conditions
“Zero Error” be positive and
negative?
Answer:
Zero error will be positive if
“zero” of circular scale is below the “Zero” of main scale and negative if
“zero” of circular scale is above the “zero” of main scale. “Zero error” is
always subtracted from the final reading to obtain accurate
result.
Q
28:- What do you mean by
“backlash error”?
Answer:
When nut or bolt becomes loose
in one another, the error in the instrument is called “backlash
error”.
Q
29:- What do you mean by area
of cross-section?
Answer:
Area of either side of edge
portion of a wire is called its area of cross-section. Its unit is
m2, cm2 or mm2. It is given by
formula.
A
= πr2
Where
r = radius of the wire.
Q
30:- What is the formula of
finding volume of a sphere?
Answer:
Volume of a sphere can be found
by formula.
V
= 
Where
r = radius of the sphere.
Q
31:- What are you doing with
spherometer?
Answer:
I am going to find radius of
curvature of a spherical surface and thickness of a glass piece with the spherometer.
Q
32:- How many scales are
there in a spherometer?
Answer:
There are two scales in a spherometer.
(i) Main
Scale
(ii) Circular
Scale
Q
33:- What are their
units?
Answer:
The unit of main scale is mm and
circular scale have no unit.
Q
34:- Why “zero” on main scale
is in the middle?
Answer:
Divisions above “zero” of main
scale are for positive reading while divisions below “zero” are for negative
reading.
Q
35:- Can we measure height or
depth or both with this instrument?
Answer:
We can measure both height and
depth with this instrument. Only main scale reading will be positive or negative
while circular scale reading will be always positive.
Q
36:- What is the least count
of spherometer?
Answer:
The least count of spherometer is 0.01mm or 0.001cm and can be found by
formula.
Least
count =
Q
37:- How can you find zero
error of spherometer?
Answer:
Base plate reading or reading on
a smooth horizontal surface is called its “zero error”
reading.
Q
38:- Why the instrument is
called “Spherometer”?
Answer:
Because it is used to find the
radius of curvature of spherical surfaces. It can also be used to find small
thickness, height or depth.
Q
39:- Why spherometer is preferred on foot scale and vernier calipers?
Answer:
Because the least count of spherometer is smaller than the least count of foot scale
and vernier calipers.
Q
40:- What do you mean by
radius of curvature?
Answer: The radius of a sphere of which the
spherical surface is the part is called its radius of
curvature.
Q
41:- What do you mean by
focal length?
Answer:
Half of the radius of curvature
of a concave mirror is called “focal Length”. OR Distance
between principle focus and pole of a concave mirror is called its “focal
length”.
Q
42:- What is the radius of
curvature of a plane mirror?
Answer:
The radius of curvature of a
plane mirror is infinity.
Q
43:- What is the focal length
of a plane mirror?
Answer:
The focal length of a plane
mirror is infinity.
Q
44:- What are you doing with
convex lens?
Answer:
I am going to find the coal
length of convex lens by no-parallax method.
Q
45:- What do you mean by
focal length of convex lens?
Answer:
Distance between optical center
of a convex lens and its principal focus is called its focal
length.
Q
46:- What do you mean by
principal focus?
Answer:
When parallel rays of light are
incident on a convex lens, the lens converges these
rays at a point called focus. If the focus is on principal axis then it is
called “principal focus”.
Q
47:- What is the other name
of convex lens?
Answer:
The other name of convex lens is
“converging lens” because it converges a beam of
parallel rays.
Q
48:- What do you mean by
no-parallax method?
Answer:
When two bodies or an object and
its image are at same distance from an eye, both bodies or object and its image
move simultaneously in the same direction i.e. right or left. Thus it is said
that there is no-parallax between them.
Q
49:- What do you mean by parallax?
Answer:
When there is relative shift
between two bodies or an object and its image, on moving the eye side way, it is
said that there is parallax between the bodies or object and its
image.
Q
50:- What do you mean by
aperture?
Answer:
The open portion of the lens
through which light can pass is called its “aperture”.
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