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Published on: 24/08/2019
Current Electricity
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.
When three resistors are connected in series then the value of the effective resistance is _______________.
less than the individual resistance
greater than the individual resistance
greater than or equal to individual resistance
less than or equal to individual resistance
2.
Generally the instantaneous current is represented by__________
i
I
dI
di
3.
The resistivity of a wire depends on _________________.
length
material
area of cross section
all the above
4.
Two identical resistors are connected in parallel then connected in series. The effective resistance are in the ratio ________________.
1:2
2:1
1:4
4:1
5.
An ideal cell is connected to a capacitor through a voltmeter. The reading V of the voltmeter is plotted against time. Which of the following best represents the resulting curve?
6.
Conductor which obey ohm's law are called ______________.
dielectrics
superconductors
ohmic conductors
semiconductors
7.
An unknown resistance is connected in parallel with a 15\(\Omega \) resistance and a 12V battery. What is the value of the unknown resistance if the current in the circuit is 2A?
\(10\Omega \)
\(20\Omega \)
\(30\Omega \)
\(40\Omega \)
8.
The emf of a battery is 3 volts and internal resistance 0.125 \(\Omega \) . The difference of potential at the terminal of battery when connected across an external resistance of 1 \(\Omega \) is ______________.
1.67 V
0.67 V
2.67 V
3.67 V
9.
An electron gun in a TV shoots out a beam of electrons. The beam current is 10\(\mu\)A. The charge that strikes the screen in 1 minute is ______________.
\(+600\mu C\)
\(-600\mu C\)
\(+10\mu C\)
\(-10\mu C\)
10.
The temperature co-efficient of resistance for alloys is _____________.
low
very low
high
very high
11.
Which of the following has negative temperature coefficient of resistance?
copper
tungsten
carbon
silver
12.
13.
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
\(\frac{R}{4}\)
\(\frac{R}{2}\)
14.
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
15.
A toaster operating at 240 V has a resistance of 120 Ω. The power is ______.
400 W
2 W
480 W
240 W
16.
Energy
17.
Power
18.
Resistance
19.
Current
20.
Electrical Lamp
1.
(b)
greater than the individual resistance
2.
(a)
i
3.
(d)
all the above
4.
(a)
1:2
5.
(b)
6.
(c)
ohmic conductors
7.
(a)
\(10\Omega \)
8.
(c)
2.67 V
9.
(b)
\(-600\mu C\)
10.
(a)
low
11.
(c)
carbon
12.
(a)
13.
\(\mathrm{V}_1 =220 \mathrm{~V}, \quad \mathrm{P}_1=60 \mathrm{~W} \)
\(\mathrm{~V}_{\mathrm{U}} =110 \mathrm{~V}, \mathrm{P}_{\mathrm{U}}=60 \mathrm{~W} \)
\(P =\frac{V^2}{R} \Rightarrow R=\frac{V^2}{P} \)
\(\therefore R_l =\frac{V_I^2}{P_l} \text { Similarly, } \quad \mathrm{R}_U=\frac{V_U^2}{P_U} \)
\(R_l =\frac{220 \times 220}{60} \quad \mathrm{R}_{\mathrm{U}}=\frac{110 \times 110}{60} \)
\(R_I =\frac{48400}{60} \quad R_U=\frac{12100}{60} \)
\(\frac{R_U}{R_l} =\frac{12100}{60} \times \frac{60}{48400}=\frac{1}{4} \)
\(R_U =\frac{R_l}{4}=\frac{R}{4}\)
14.
Yellow - 4
Violet - 7
Orange - 103
Silver - Tolerance - 10%
15.
\(P=\frac{V^2}{R}=\frac{240 \times 240}{120}=480 \ W\)
16.
joule
17.
watt
18.
ohm
19.
ampere
20.
Tungsten
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