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TN 12th Computer Applications வலையமைப்பு வடமிடல் Sample Question Papers Study Material - QB365 Set A
Published on: 28/11/2025
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.
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1.
The resistance of a uniform wire of length l and cross-sectional area A is R. The resistance of wire of the same material having length 2l and cross sectional area 2A is:
R
2R
R/2
R/4
2.
For the fuse wire, which of the following characteristic is immaterial?
Radius
Resistivity
Length
None of these
3.
If a current of 7.5 A is maintained in a wire for 45 s then the charge flowing through the wire is :
6 C
365.5 C
3 C
337.5 C
4.
As the temperature increases, the electrical resistance
Increases for both conductors and semiconductors
Decreases for both conductors and semiconductors
Increases for conductors but decreases for semiconductors
Decreases for conductors but increases for semiconductors
5.
The resistors each of resistance \(1 \Omega\) is connected as shown in the figure. The resultant resistance between A and B is
\(\frac{11}{5} \Omega\)
\(\frac{5}{11} \Omega\)
\(\frac{6}{5} \Omega\)
\(\frac{6}{5} \Omega\)
6.
Kirchoff's I and II laws are based on conservation of ______________.
charge and energy
energy and charge
energy and voltage
energy and current
7.
Dimension of Resistance is _____.
ML2 T-3 A-2
ML2 T-1 A-1
ML2 T-2A-3
ML2 T-1A-2
8.
Resistance of resistor having colour code Yellow - Green - Red - Gold.
\((4700 \pm 5 \%) \Omega\)
\((4500 \pm 5 \%) \Omega\)
\((4700 \pm 10 \%) \Omega\)
\((4500 \pm 10 \%) \Omega\)
9.
RMS voltage and frequency of v = 230 sin (314 t) A.C. source.
162.6V, 50Hz
230V, 50Hz
230V, 60Hz
162.6V, 25Hz
10.
According to Joule's law of heating, heat is given by _______________.
H = VIt
H = I2 Rt
both a & b
None of the above
11.
The equivalent emf \(\varepsilon_{\mathrm{cq}}\) and the equivalent internal resistance of the following circuit are ___________.
9 V and \(3 \Omega\)
3 V and \(0.33 \Omega\)
6 V and \(0.3 \Omega\)
1 V and \(3 \Omega\)
12.
The unit of mobility of free electron is ______________.
Vm-1 s-2
m2 Vs-1
m2 V-1s-1
m2 V-1s
13.
Potentiometer is an instrument used for the measurement of____________
current
resistance
capacitance
potential difference
14.
In the case of meter bridge manganin wire is used because it has_________
low temperature coefficient of resistance
high temperature coefficient of resistance
temperature coefficient of resistance is zero
temperature coefficient of resistance is maximum
15.
When the diameter of a conductor is doubled its resistance_________
decreases twice
decreases four times
decreases sixteen times
increases four times
16.
17.
A piece of copper and another of germanium are cooled from room temperature to 80 K. The resistance of ______.
each of them increases
each of them decreases
copper increases and germanium decreases
copper decreases and germanium increases
18.
The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is ______.
0.2 Ω
0.5 Ω
0.8 Ω
1.0 Ω
19.
The temperature coefficient of resistance of a wire is 0.00125 per °C. At 20°C, its resistance is 1 Ω. The resistance of the wire will be 2 Ω at ______.
800 °C
700 °C
850 °C
820 °C
20.
What is the current drawn out from the battery?
1 A
2 A
3 A
4 A
21.
There is a current of 1.0 A in the circuit shown below. What is the resistance of P ?
1.5 Ω
2.5 Ω
3.5 Ω
4.5 Ω
22.
In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW are connected. The voltage of electric mains is 220 V. The maximum capacity of the main fuse of the building will be ______.
14 A
8 A
10 A
12 A
23.
In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be ______.
R
2R
\(\frac{R}{4}\)
\(\frac{R}{2}\)
24.
A wire connected to a power supply of 230 V has power dissipation P1. Suppose the wire is cut into two equal pieces and connected parallel to the same power supply. In this case power dissipation is P2. The ratio \(\frac{P_2}{P_1}\) is ______.
1
2
3
4
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
\(\sqrt3\)
\(\frac{1}{\sqrt3}\)
\(\frac{1}{3}\)
26.
What is the value of resistance of the following resistor?
100 k Ω
10 k Ω
1 k Ω
1000 k Ω
27.
A carbon resistor of (47 ± 4.7 ) k Ω to be marked with rings of different colours for its identification. The colour code sequence will be ______.
Yellow – Green – Violet – Gold
Yellow – Violet – Orange – Silver
Violet – Yellow – Orange – Silver
Green – Orange – Violet - Gold
28.
A toaster operating at 240 V has a resistance of 120 Ω. The power is ______.
400 W
2 W
480 W
240 W
29.
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\(\pi \Omega\)
\(\frac{\pi}{4}\Omega\)
30.
The following graph shows current versus voltage values of some unknown conductor. What is the resistance of this conductor?
2 ohm
4 ohm
8 ohm
1 ohm
1.
(a)
R
2.
(c)
Length
3.
(a)
6 C
4.
(c)
Increases for conductors but decreases for semiconductors
5.
(b)
\(\frac{5}{11} \Omega\)
6.
(a)
charge and energy
7.
\(R=\frac{V}{I}=\frac{W}{q I}=\frac{W}{I t \times I}=\frac{W}{I^2 t}\)
Dimension of \( \mathrm{W} \rightarrow\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right] \)
Dimension of \( I \rightarrow[A] \)
Dimension of \(t \rightarrow[\mathrm{T}]\)
Hence,
\( [R]=\frac{\left.\mid \mathrm{ML}^2 \mathrm{~T^-2}\right]}{\left[\mathrm{A}^2 \mathrm{~T}\right]}=\left[\mathrm{ML}^2 \mathrm{~T}^{-3} \mathrm{~A}^{-2}\right] \)
8.
\(\text { Yellow } \rightarrow 4 \text {, Green } \rightarrow 5 \text {, Red } \rightarrow 10^2 \text {,Gold} \rightarrow5\)%
So, resistance of the resistor is,
\(45 \times 10^2 \pm 5 \%=4500 \pm 5 \% \Omega\)
9.
(a)
162.6V, 50Hz
10.
(c)
both a & b
11.
(i) Equivalent emf \(\varepsilon_{\mathrm{eq}}\) = 3 V
(ii) Equivalent internal resistance is,
\(R_{\text {eq }}=\frac{r}{n}=\frac{1}{3}=0.33 \Omega\)
12.
(c)
m2 V-1s-1
13.
(a)
current
14.
(c)
temperature coefficient of resistance is zero
15.
(d)
increases four times
16.
(a)
17.
Resistivity ∝ temperature for conductor. so, copper → decreases
Resistivity ∝\(\frac{1}{\text {temperature for semiconductor}}\)
so, germanium → increases.
18.
I = 0.2 A, R = 10 Ω, E = 2.1 V
\(I=\frac{ɛ}{R+r}\)
\(0.2=\frac{2.1}{10+r}\)
0.2 x (10 + r) = 2.1
2 + 0.2 r = 2.1
0.2 r = 2.1 - 2 = 0.1
Internal resistance, \(r=\frac{0.1}{0.2}=\frac{1}{2}\)
r = 0.5 Ω
19.
Rt = Ro [1 + α(T2 - T1)
2 = 1[1 + 0.00125(T2 - 293)
I = 5/4 x 10-3 (T2 - 293)
T2 = 1093 K
T2 = 820 oC
20.
\(\frac{1}{R_p}=\frac{1}{15}+\frac{1}{15}+\frac{1}{15}.\)
\(=\frac{1+1+1}{15}=\frac{3}{15}=\frac{1}{5}\)
∴ Rp = 5 Ω
\(\therefore I=\frac{V}{R_p}=\frac{5}{5}=1A\)
21.
Rs = 3 + 2.5 + P = 5.5 + P
V = 9 V, I = 1.0 A
Rs = \(\frac{V}{I}=\frac{9}{1}= 9 \Omega\)
∴ 9 = 5.5 + P
∴ P = 9 - 5.5 = 3.5 Ω
22.
Total power = 15 x 40 + 5 x 100 + 5 x 80 + 1000
= 600 + 500 + 400 + 1000
= 2500 W
P = VI, V = 220 V
\(I=\frac{P}{V}=\frac{2500}{220}=11.363 \ A\)
≃ 12 A
23.
\(\mathrm{V}_1 =220 \mathrm{~V}, \quad \mathrm{P}_1=60 \mathrm{~W} \)
\(\mathrm{~V}_{\mathrm{U}} =110 \mathrm{~V}, \mathrm{P}_{\mathrm{U}}=60 \mathrm{~W} \)
\(P =\frac{V^2}{R} \Rightarrow R=\frac{V^2}{P} \)
\(\therefore R_l =\frac{V_I^2}{P_l} \text { Similarly, } \quad \mathrm{R}_U=\frac{V_U^2}{P_U} \)
\(R_l =\frac{220 \times 220}{60} \quad \mathrm{R}_{\mathrm{U}}=\frac{110 \times 110}{60} \)
\(R_I =\frac{48400}{60} \quad R_U=\frac{12100}{60} \)
\(\frac{R_U}{R_l} =\frac{12100}{60} \times \frac{60}{48400}=\frac{1}{4} \)
\(R_U =\frac{R_l}{4}=\frac{R}{4}\)
24.
\(\mathrm{V}=230 \mathrm{~V} \)
\(P=\frac{V^2}{R} \text { since } \mathrm{V} \text { is same } \mathrm{P} \propto \frac{1}{R} \)
\(\frac{1}{R_2}=\frac{1}{\frac{R_1}{2}}+\frac{1}{\frac{R_1}{2}}=\frac{2}{R_1}+\frac{2}{R_1}=\frac{2+2}{R_1} \)
\(\frac{1}{R_2}=\frac{4}{R_1} \)
\(\therefore R_2=\frac{R_1}{4} \)
\(R_1=4 R_2 \)
\(\therefore \frac{P_2}{P_1}=\frac{R_1}{R_2}=\frac{4 R_2}{R_2}=4\)
25.
\(R \propto \frac{1}{A}, R \propto \frac{1}{r^2} \)
\(R_A \propto \frac{1}{r_A^2}, R_B \propto \frac{1}{r_B^2} \)
\(\frac{r_A}{r_B}=\left(\frac{R_B}{R_A}\right)^{1 / 2}=\left(\frac{R_B}{3 R_B}\right)^{1 / 2}=\frac{1}{3^{\frac{1}{2}}}=\frac{1}{\sqrt{3}}\)
26.
Brown - 1
Black - 0
Yellow - 104
(∴ R = 10 x 104 Ω = 100 kΩ)
27.
Yellow - 4
Violet - 7
Orange - 103
Silver - Tolerance - 10%
28.
\(P=\frac{V^2}{R}=\frac{240 \times 240}{120}=480 \ W\)
29.
Total length = 2πr = 2π
∴ Resistance of each segment = 2π/2 = π Ω
30.
Resistance, \(R=\frac{V}{I}=\frac{4}{2}=2 \ ohm\)
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