12th Standard Syllabus & Materials
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TN 12th Computer Applications மின்னணு தரவு பரிமாற்றம் Sample Question Papers Study Material - QB365 Set A
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TN 12th Computer Applications மின்னணு செலுத்தல் முறைகள் Sample Question Papers Study Material - QB365 Set A
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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 திறந்த மூல கருத்துருக்கள் 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 Three
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.
A point source of light B is placed at a distance L in front of the center of a mirror of width d hung vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance of 2 L front it as shown. The greatest distance over which he can see the image of the light source in the mirror is ___________.
d/2
d
2d
3d
2.
Output characteristics of an NPN, transistor in CE mode is drawn between ___________
IC and VBE
IE and VCE
IB and VCE
IC and VCE
3.
Electron microscope operates in ______ media.
UV
X-ray
complete vacuum
air
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.
Two photons each of energy 2.5 eV are simultaneously incident on the metal surface. If the work function of the metal is 4.5 eV then from the surface of the metal ______________.
one electron will be emitted
two electrons will be emitted
more than two electrons will be emitted
not a single electron will be emitted
6.
Millikan's oil drop experiment established that is ____________.
electric charge depends on velocity
electric charge is quantised
electron has wave nature
electron has particle nature
7.
The internationally accepted frequency deviation for the purpose of FM broadcasts ____________.
75 kHz
68 kHz
80 kHz
70 kHz
8.
The electric potential of an electron is given by \(V={ V }_{ 0 } \ In\left( \frac { r }{ { r }_{ 0 } } \right) \), where r0 is a constant. If Bohr atom model is valid, then variation of radius of nth orbit rn with the principal quantum number n is _____.
\({ r }_{ n }∝ \frac { 1 }{ n } \)
\({ r }_{ n }∝ n\)
\({ r }_{ n }∝\frac { 1 }{ { n }^{ 2 } } \)
\({ r }_{ n }∝ { n }^{ 2 }\)
9.
Atomic number of H-like atom with ionization potential 122.4 V for n = 1 is _____.
1
2
3
4
10.
11.
A ray of light travelling in a transparent medium of refractive index n falls, on a surface separating the medium from air at an angle of incidents of 45o . The ray can undergo total internal reflection for the following n, ______.
n = 1.25
n = 1.33
n = 1.4
n = 1.5
12.
A magnetic field is produced by ____________.
a changing electric field
a moving charge
both of them
none of them
13.
Lorentz force generally refers to force experienced by a charge due to combined action of _________________.
magnetic fields
electric fields
electric, magnetic & gravitational fields
electric and magnetic fields
14.
Kirchhoff's I law is a consequence of__________
law of conservation of energy
law of conservation of charges
law of conservation of currents
law of conservation of voltages
15.
Which current- time graph represents the steady movement of short magnet through a coil XY?
.JPG)
.JPG)
.JPG)
.JPG)
16.
Gauss law is another form of ________.
Newton's law
Kepler's law
Ohm's law
Coulomb's law
17.
Surface density of charge on a sphere of radius R in terms of electric intensity E at a distance r in free space is
\({ \varepsilon }_{ 0 }E{ \left( \frac { R }{ r } \right) }^{ 2 }\)
\(\frac { { \varepsilon }_{ 0 }ER }{ { r }^{ 2 } } \)
\({ \varepsilon }_{ 0 }E{ \left( \frac { r }{ R } \right) }^{ 2 }\)
\({ e }_{ 0 }E\frac { r }{ { R }^{ 2 } } \)
18.
A charge Q μ C is placed at the center of a cube. The flux coming out from any surface will be
\(\frac { Q }{ { 24\varepsilon }_{ 0 } } \)
\(\\ \frac { Q }{ { 8\varepsilon }_{ 0 } } \)
\(\frac { Q }{ { 6\varepsilon }_{ 0 } } \times { 10 }^{ -6 }\)
\(\frac { Q }{ { 6\varepsilon }_{ 0 } } \times { 10 }^{ -3 }\)
19.
The negative gradient of potential is
torque
electric current
electric field intensity
electric force
20.
Charge per unit volume is called _____________
Linear charge density (λ)
Surface charge density (σ)
Volume charge density (ρ)
Electric flux
21.
Three wires of equal lengths are bent in the form of loops. One of the loops is circle, another is a semi-circle and the third one is a square. They are placed in a uniform magnetic field and same electric current is passed through them. Which of the following loop configuration will experience greater torque?
Circle
Semi-circle
Square
All of them
22.
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
23.
Which of the following is NOT true for electromagnetic waves?
it transport energy
it transport momentum
it transport angular momentum
in vacuum, it travels with different speeds which depend on their frequency
24.
An electric field \(\vec { E } =10x\hat { i } \) exists in a certain region of space. Then the potential difference V = Vo – VA, where Vo is the potential at the origin and VA is the potential at x = 2 m is _____.
10 V
-20 V
+20 V
-10 V
25.
Two wires of A and B with circular cross section made up of the same material with equal lengths. Suppose RA = 3 RB, then what is the ratio of radius of wire A to that of B?
3
\(\sqrt3\)
\(\frac{1}{\sqrt3}\)
\(\frac{1}{3}\)
1.
(d)
3d
2.
(a)
IC and VBE
3.
(c)
complete vacuum
4.
(d)
all of the above
5.
(d)
not a single electron will be emitted
6.
(b)
electric charge is quantised
7.
(a)
75 kHz
8.
Electric potential in nth orbit
\(\mathrm{V} =\mathrm{V}_0 \ln \left(\frac{\mathrm{r}_{\mathrm{n}}}{\mathrm{r}_0}\right) \)
\(=\mathrm{V}_0\left(\ln \mathrm{r}_{\mathrm{n}}-\ln \mathrm{r}_0\right) \)
\(=\mathrm{V}_0 \ln \mathrm{r}_{\mathrm{n}}-\mathrm{V}_0 \ln \mathrm{r}_0\)
\(\left|\mathrm{F}_\epsilon\right|=\mathrm{e} \frac{\mathrm{dv}}{\mathrm{dr}} =\mathrm{e} \frac{\mathrm{d}}{\mathrm{dr}}\left(\mathrm{V}_b / n \mathrm{r}_B-\mathrm{V}_0 / m \mathrm{r}_0\right) \)
\(=\mathrm{c}\left(\frac{\mathrm{V}_0}{\mathrm{r}_n}-0\right)=\frac{\mathrm{eV}}{\mathrm{r}_{\mathrm{n}}} \)
Centripetal force = coulomb force
\(\frac{m v^2}{r_n}=\mathrm{c} \frac{V_0}{r_n} \Rightarrow v=\sqrt{\frac{e V_0}{m}}=\text { constant }\)
Angular momentum,
\(\mathrm{mvr}_n=\frac{\mathrm{nh}}{2 \pi}\)
\(\mathrm{m}, \mathrm{v}, \mathrm{h}, 2 \pi\) are constants
hence, rn ∝ n
9.
\(V_{ionisation}=\frac{13.6}{n^2}Z^2 volt\)
\(Z=\sqrt\frac{V\times n^2}{13.6}=\sqrt\frac{122.4 \times I^2}{13.6}=\sqrt{9}=3\)
10.
(b)
11.
For total internal reflection,
sin i > sin c
\(n=\frac{1}{sin \ c}\)
\(sin \ c=\frac{1}{n}\)
\(sin \ i>\frac{1}{n}\)
\(n>\frac{1}{sin \ i}\)
n >\(\sqrt{2}\)
n >1.414 = 1.5
12.
(c)
both of them
13.
(d)
electric and magnetic fields
14.
(b)
law of conservation of charges
15.
(a)
16.
(d)
Coulomb's law
17.
(c)
\({ \varepsilon }_{ 0 }E{ \left( \frac { r }{ R } \right) }^{ 2 }\)
18.
(c)
\(\frac { Q }{ { 6\varepsilon }_{ 0 } } \times { 10 }^{ -6 }\)
19.
(c)
electric field intensity
20.
(c)
Volume charge density (ρ)
21.
(a)
Circle
22.
\(\Phi = \frac{\pi}{3}-\frac{\pi}{3}=0 \)
Power factor = cosФ = cos 0 = 1
23.
(d)
in vacuum, it travels with different speeds which depend on their frequency
24.
\(\vec {E}\) = 10x\(\hat{i},\) when x = 2 m
\(\vec {E}\) = 10 x 2 x \(\hat{i}\) = 20\(\hat{i}\)
Since, \(E=\frac{-dV}{dx}\therefore V=+20 V\)
25.
\(R \propto \frac{1}{A}, R \propto \frac{1}{r^2} \)
\(R_A \propto \frac{1}{r_A^2}, R_B \propto \frac{1}{r_B^2} \)
\(\frac{r_A}{r_B}=\left(\frac{R_B}{R_A}\right)^{1 / 2}=\left(\frac{R_B}{3 R_B}\right)^{1 / 2}=\frac{1}{3^{\frac{1}{2}}}=\frac{1}{\sqrt{3}}\)
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