12th Standard Syllabus & Materials
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TN 12th Computer Applications மின் - வணிகம் Sample Question Papers Study Material - QB365 Set A
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TN 12th Computer Applications வலையமைப்பு வடமிடல் Sample Question Papers Study Material - QB365 Set A
Published on: 12/10/2020
12th Standard Physics English Medium Free Online Test one mark questions with answer key 2020 Part Ten
Download Tamil Nadu 12th Standard Physics question papers, model tests, one-mark questions, important questions, and public exam papers in PDF format. Free study materials and answer keys for TN State Board students.
Questions + Answers key
Take MCQ Physics Test1.
If an object moves towards a plane mirror with a speed V at an angle θ to the perpendicular to the plane of the mirror, find the relative velocity between the object and the image ____________.
V
2V
2 V cosθ
2 V sin θ
2.
Photoelectric cells are used to control _______ of furnaces.
pressure
temperature
output power
input
3.
If the distance between the conduction band and valence band is leV, then this combination is _______________.
semiconductor
metal
insulator
conductor
4.
Optical fiber communication is generally preferred over general communication system because ____________.
it has signal security
it is more efficient
it cannot be jammed as easily as radio waves
all of the above
5.
FM broad cost is preferred over AM broadcast because _______________.
It is less noisy
reproduction is of much better quality
it is more noisy
both (a) & (b)
6.
Large band width for higher data is achieved by using ________________.
Large bandwidth for higher data is achieved
high frequency audio wave
low frequency carrier wave
low frequency audio wave
7.
The expression of Y in the following circuit is _______________.
AB + CD
A + BCD
A + B + C + D
A. B. C. D
8.
Which of the following is not the advantage of PN junction diode over tube value?
Unlimited life
No warming-up time after switching
Large efficiency
Low consumption of power
9.
A good _____ slows down neutrons by elastic collisions and it does not remove them by absorption.
fuel
moderator
coolant
control rod
10.
The charge of an alpha-particle is _______________
same as that of a proton
twice as that of an electron
thrice as that of an proton
twice as that of a neutron
11.
An a-particle of energy 10 meV is scattered through 180o by a fixed uranium nucleus. The distance of the closest approach is of the order of _____________.
1Å
10-10 cm
10-12 cm
10-15 cm
12.
If the mean wavelength of light from sun is taken as 550 nm and its mean power as 3.8 x 1026 W, then the number of photons emitted per second from the sun is of the order of _____.
1045
1042
1054
1051
13.
The wave associated with a moving particle of mass 3 x 10–6 g has the same wavelength as an electron moving with a velocity 6 x 106 ms-1. The velocity of the particle is _____.
1.82 x 10-18ms-1
9 x 10-2ms-1
3 x 10-31ms-1
1.82 x 10-15ms-1
14.
The radius of curvature of curved surface at a thin planoconvex lens is 10 cm and the refractive index is 1.5. If the plane surface is silvered, then the focal length will be, ______.
5 cm
10 cm
15 cm
20 cm
15.
Which of the following E.M waves has the longest wavelength?
Radio waves
IR
X-rays
visible
16.
What is the current passing through a coil of radius of 8 cm having 50 turns, when a magnetic intensity at the centre of the coil is 125 A turns m-1?
0.1 ampere
0.4 ampere
1 ampere
4 ampere
17.
Unit of inductive reactance is ___________
ohm-metre
mho-metre-1
ohm
mho
18.
When a current of 5 A flows through a conductor of resistance 3 \(\Omega \) the loss of power due to joule heating effect is_________
75 W
25 W
70.7 W
45 W
19.
Temperature co-effieient of resistance for metals is ______________.
constant
positive
zero
negative
20.
Which of the following cannot be the units of electric field intensity?
NC-1
Vm-1
JC-1/m
JC-1
21.
The electric field created by a _________ is basically a non-uniform electric field.
Test charge
Positive charge
Negative charge
Point charge
22.
An electron moves in a straight line inside a charged parallel plate capacitor of uniform charge density σ. The time taken by the electron to cross the parallel plate capacitor undeflected when the plates of the capacitor are kept under constant magnetic field of induction \((\vec{B})\) is
\({ \varepsilon }_{ ° }\frac { elB }{ \sigma } \)
\({ \varepsilon }_{ ° }\frac { lB }{ \sigma {l} } \)
\({ \varepsilon }_{ ° }\frac { lB }{ {e}\sigma } \)
\({ \varepsilon }_{ ° }\frac { lB }{ \sigma } \)
23.
In an electrical circuit, R, L, C, and AC voltage source are all connected in series. When L is removed from the circuit, the phase difference between the voltage and current in the circuit is \(\frac{\pi}{3}\). Instead, if C is removed from the circuit, the phase difference is again \(\frac{\pi}{3}\). The power factor of the circuit is
1/2
1/\(\sqrt2\)
1
\(\sqrt3\)/2
24.
If voltage applied on a capacitor is increased from V to 2V, choose the correct conclusion.
Q remains the same, C is doubled
Q is doubled, C doubled
C remains same, Q doubled
Both Q and C remain same
25.
A wire of resistance 2 ohms per meter is bent to form a circle of radius 1m. The equivalent resistance between its two diametrically opposite points, A and B as shown in the figure is
\(\pi \Omega\)
\(\frac{\pi}{2}\Omega\)
2\(\pi \Omega\)
\(\frac{\pi}{4}\Omega\)
1.
(c)
2 V cosθ
2.
(b)
temperature
3.
(a)
semiconductor
4.
(d)
all of the above
5.
(d)
both (a) & (b)
6.
(a)
Large bandwidth for higher data is achieved
7.
(c)
A + B + C + D
8.
(a)
Unlimited life
9.
(b)
moderator
10.
(b)
twice as that of an electron
11.
(c)
10-12 cm
12.
\(\mathrm{P} =\frac{\mathrm{n}}{\mathrm{t}} \frac{\mathrm{hc}}{\lambda} \)
\(\frac{\mathrm{n}}{\mathrm{t}} =\frac{\mathrm{P} \lambda}{\mathrm{hc}} \)
\(\frac{\mathrm{n}}{\mathrm{t}} =\frac{3.8 \times 10^{26} \times 550 \times 10^{-9}}{6.6 \times 10^{-3} \times 3 \times 10^8}=1 \times 10^{-15}\)
13.
\(\lambda_{\mathrm{i}} \frac{1}{\mathrm{mv}} \)
\(\frac{\lambda_p}{\lambda_e} =\frac{m_e v_e}{m_P v_P} \)
\(1 =\frac{9.1 \times 10^{-31} \times 6 \times 10^6}{3 \times 10^{-9} \times v_p} \)
\(\mathrm{v}_{\mathrm{p}} =9.1 \times 10^{-16} \times 2 \)
\(\mathrm{v}_{\mathrm{p}} =18.2 \times 10^{-16} \)
\(\mathrm{v}_{\mathrm{p}} =1.82 \times 10^{-15} \mathrm{~m} \mathrm{~s}^{-1}\)
14.
\(\frac{1}{f} =(n-1)\left(\frac{1}{R_1}-\frac{1}{R_2}\right) \)
\(=(1.5-1)\left(\frac{1}{\infty}-\frac{1}{(-10)}\right)\)
(Since plano convex lens)
\(=0.5\left[\frac{1}{10}\right]=\frac{1}{20} \)
\(\mathrm{f}_t =20 \mathrm{~cm}\)
Formula for silvered lenses
\(\frac{1}{\mathrm{~F}} =\frac{2}{\mathrm{f}_1}+\frac{1}{\mathrm{f}_m} \)
\(\frac{1}{\mathrm{~F}} =\frac{2}{20}+\frac{1}{\infty} \)
\(\therefore \mathrm{F} =\frac{20}{2}=10 \mathrm{~cm}\)
15.
(a)
Radio waves
16.
(b)
0.4 ampere
17.
(c)
ohm
18.
(a)
75 W
19.
(b)
positive
20.
(d)
JC-1
21.
(d)
Point charge
22.
Electric field between the plates \(= \frac{σ}{ε_0}\)
Electric force on an electron \(= e\frac{σ}{ε_0}\)
Magnetic force on an electron, F = BIl
But, \(I= \frac{e}{t}\)
∵Electron moves in a straight line. So,
EF = MF
\(e\frac{σ}{ε_0}=B(\frac{e}{t})l\)
\(\therefore t = ε_0\frac{lB}{σ}\)
23.
\(\Phi = \frac{\pi}{3}-\frac{\pi}{3}=0 \)
Power factor = cosФ = cos 0 = 1
24.
If voltage is increased from V to 2 V
Then Q1 = CV
Q2 = C(2 V) = 2 CV
∴ Q is doubled and C remains same
25.
Total length = 2πr = 2π
∴ Resistance of each segment = 2π/2 = π Ω
12th Standard Syllabus & Materials
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