12th Standard Syllabus & Materials
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TN 12th English Poem - 6 - Incident of the French Camp Sample Question Papers Study Material - QB365 Set A
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TN 12th English Prose - 5 - The Chair Sample Question Papers Study Material - QB365 Set A
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TN 12th English Supplementary - 4 - The Midnight Visitor Sample Question Papers Study Material - QB365 Set A
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TN 12th English Prose - 4 - The Summit Sample Question Papers Study Material - QB365 Set A
Published on: 13/10/2020
12th Standard Physics Electromagnetic Induction and Alternating Current English Medium Free Online Test One Mark questions 2020 - 2021
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.
In RLC series AC circuit at resonance __________.
Resistance is zero
Net reactance is zero
impedance is maximum
voltage leads the current by a phase angle \(\frac{ㅠ}{2}\)
2.
The average power consumed per cycle is ______________.
Zero
2000 W
1000 W
500 W
3.
In LCR series circuit, at resonance is ___________
impedance (Z) is maximum
current is minimum
impedance (Z) is equal to R
vo = \(\frac{1}{LC}\)
4.
Inductive reactance, XL = ?
2πnL
\(\frac { 2\pi v }{ L } \)
\(\frac { 2\pi }{ vL } \)
\(\frac { 2\pi }{ vL } \)
5.
An alternating current has _______________.
only positive value
only negative value
both positive and negative value
steady value
6.
Flux loss can be minimized using ________ core.
laminated
shell-type
perforated
sheet-type
7.
A transformer is _____________.
converts energy
changes voltage
changes current
changes both current and voltage
8.
The necessary magnetic field for a low power a.c generator is produced by _________
electric coil
permanent magnets
electromagnets
batteries
9.
The self inductance of a coil is ________________.
directly proportional to N
inversely proportional to N
directly proportional to N2
inversely proportional to N2
10.
In Fleming's right hand rule, the forefinger represents the direction of ____________.
motion of the conductor
magnetic field
induced current
induced emf
11.
In the following figure the key is dosed. Which statement is correct?
momentary current flows in Y circuit from B to A
momentary current flows in Y circuit from A to B
no current flows along AB
the coil Y is attracted to X
12.
The magnitude of the induced emf in a conductor depends on the _______________.
flux density of the magnetic field
amount of flux cut
amount of flux linkages
rate of change of flux
13.
Transformer works on _____________.
AC only
DC only
both AC and DC
AC more effectively than DC
14.
An emf of 12V is induced when the current in the coil changes at the rate of 40 A S-1. The coefficient of self induction of the coil is __________________.
0.3 H
0.003 H
30 H
4.8 H
15.
The unit henry can also be written as ______________.
VS A-1
Wb A-1
Ωs
all
16.
Electromagnetic induction is-not used in ___________________.
transformer
room heater
AC generator
choke coil
17.
The instantaneous values of alternating current and voltage in a circuit are \(i=\frac { 1 }{ \sqrt { 2 } } \sin\left( 100\pi t \right) \) A and v \(=\frac { 1 }{ \sqrt { 2 } } \sin\left( 100\pi t+\frac { \pi }{ 3 } \right) V.\)The average power in watts consumed in the circuit is
\(\frac{1}{4}\)
\(\frac{\sqrt3}{4}\)
\(\frac{1}{2}\)
\(\frac{1}{8}\)
18.
19.
The flux linked with a coil at any instant t is given by \(\Phi\)B = 10t2 − 50t + 250. The induced emf at t = 3s is
−190 V
−10 V
10 V
190 V
20.
An electron moves on a straight line path XY as shown in the figure. The coil abcd is adjacent to the path of the electron. What will be the direction of current, if any, induced in the coil?
The current will reverse its direction as the electron goes past the coil
No current will be induced
abcd
adcb
1.
(b)
Net reactance is zero
2.
(c)
1000 W
3.
(c)
impedance (Z) is equal to R
4.
(a)
2πnL
5.
(c)
both positive and negative value
6.
(b)
shell-type
7.
(d)
changes both current and voltage
8.
(b)
permanent magnets
9.
(a)
directly proportional to N
10.
(b)
magnetic field
11.
(b)
momentary current flows in Y circuit from A to B
12.
(d)
rate of change of flux
13.
(a)
AC only
14.
(a)
0.3 H
15.
(d)
all
16.
(b)
room heater
17.
Pav = \(\frac{1}{2}\)V0I0cosΦ
\(= \frac{1}{2}\times\frac{1}{\sqrt{2}}\times\frac{1}{\sqrt{2}}cos\times\frac{\pi}{3}\times \frac{1}{2}\times\frac{1}{2}\times\frac{1}{2}=\frac{1}{8}\)
18.
(a)
19.
\(\phi_B =10 t^2-50 t+250 \)
\(e =\frac{-d \phi_B}{d t} \)
\(=\frac{-d}{d t}\left(10 t^2-50 t+250\right) \)
=-(20 t - 50)
=-20 t + 50
When, t = 3 s, e =-20(3) + 50 = -60 + 50
e = -10V
20.
The direction of conventional current is always opposite to the direction of flow of electrons.
12th Standard Syllabus & Materials
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