CBSE 12th Physics (Term 1) Paper 2021-22
CBSE 2021 Previous Year
3 hDuration
42Total Marks
55Questions
1Sections
Instructions
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Paper Structure
Physics
Physics
Q1.
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Which of the following has negative temperature coefficient of resistivity?
Q2.
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A coil of area 100 cm^(2) is kept at an angle of 30$$^\circ$$ with a magnetic field of 10^($$-$$1) T. The magnetic field is reduced to zero in 10^($$-$$4) s. The induced emf in the coil is -
Q3.
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The current in the primary coil of a pair of coils changes from 7 A to 3 A in 0.04 s. The mutual inductance between the two coils is 0.5 H. The induced emf in the secondary coil is -
Q4.
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The self-inductance of a solenoid of 600 turns is 108 mH. The self-inductance of a coil having 500 turns with the same length, the same radius and the same medium will be
Q5.
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Assertion (A) : The poles of a bar magnet cannot be separated.
Reason (R) : Magnetic monopoles do not exist.
Q6.
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A bar magnet has magnetic dipole moment $$\overrightarrow M $$. Its initial position is parallel to the direction of uniform magnetic field $$\overrightarrow B $$. In this position, the magnitudes of torque and force acting on it respectively are -
Q7.
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The horizontal component of earth's magnetic field at a place is 0.2 G whereas it's total magnetic field is 0.4 G. The angle of dip at the place is
Q8.
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Which of the following statements is correct?
Q9.
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Assertion (A) : A negative charge in an electric field moves along the direction of the electric field.
Reason (R) : On a negative charge a force acts in the direction of the electric field.
Q10.
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A negatively charged object X is repelled by another charged object Y. However an object Z is attracted to object Y. Which of the following is the most possibility for the object Z?
Q11.
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A + 3.0 nC charge Q is initially at rest at a distance of r~1~ = 10 cm from a + 5.0 nC charge q fixed at the origin. The charge Q is moved away from q to a new position at r~2~ = 15 cm. In this process work done by the field is
Q12.
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An object has charge of 1 C and gains 5.0 $$\times$$ 10^(18) electrons. The net charge on the object becomes -
Q13.
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A square sheet of side 'a' is lying parallel to XY plate at z = a. The electric field in the region is $$\overrightarrow E = c{z^2}\widehat k$$. The electric flux through the sheet is
Q14.
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Three charges q, $$-$$q and q~0~ are placed as shown in figure. The magnitude of the net force on the charge q~0~ at point O is $$\left[ {k = {1 \over {(4\pi { \in _0})}}} \right]$$
Q15.
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The electric potential V at any point (x, y, z) is given by V = 3x^(2) where x is in metres and V in volts. The electric field at the point (1 m, 0, 2m) is -
Q16.
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The magnitude of electric field due to a point charge 2q, at distance r is E. Then the magnitude of electric field due to a uniformly charged thin spherical shell of radius R with total charge q at a distance $${r \over 2}(r > > R)$$ will be
Q17.
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In an experiment three microscopic latex spheres are sprayed into a chamber and became charged with charges +3e, +5e and $$-$$3e respectively. All the three spheres came in contact simultaneously for a moment and got separated. Which one of the following are possible values for the final charge on the spheres?
Q18.
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Four charges $$-$$q, $$-$$q, +q and +q are placed at the corners of a square of side 2 L is shown in figure. The electric potential at point A midway between the two charges +q and +q is -
Q19.
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Equipotentials at a large distance from a collection of charges whose total sum is not zero are -
Q20.
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Four objects W, X, Y and Z, each with charge +q are held fixed at four points of a square of side d as shown in the figure. Objects X and Z are on the midpoints of the sides of the square. The electrostatic force exerted by object W on object X is F. Then the magnitude of the force exerted by object W on Z is
Q21.
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Two charges 14 $$\mu$$C and $$-$$4 $$\mu$$C are placed at ($$-$$12 cm, 0, 0) and (12 cm, 0, 0) in an external electric field $$E = \left( {{B \over {{r^2}}}} \right)$$, where B = 1.2 $$\times$$ 10^(6) N/(cm^(2)) and r is in metres. The electrostatic potential energy of the configuration is
Q22.
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Which of the diagrams correctly represents the electric field between two charged plates if a neutral conductor is placed in between the plates?
Q23.
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A variable capacitor is connected to a 200 V battery. If its capacitance is changed from 2 $$\mu$$F to X $$\mu$$F, the decrease in energy of the capacitor is 2 $$\times$$ 10^($$-$$2) J. The value of X is -
Q24.
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The magnetic field at the centre of a current carrying circular loop of radius R is B~1~. The magnetic field at a point on its axis at a distance R from the centre of the loop is B~2~. Then the ratio (B~1~ / B~2~) is
Q25.
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A current carrying wire kept in a uniform magnetic field, will experience a maximum force when it is
Q26.
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A straight conducting rod of length l and mass m is suspended in a horizontal plane by a pair of flexible strings in a magnetic field of magnitude B. To remove the tension in the supporting strings, the magnitude of the current in the wire is
Q27.
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A proton and an alpha particle move in circular orbits in a uniform magnetic field. Their speeds are in the ratio of 9 : 4. The ratio of radii of their circular orbits $$\left( {{{{r_p}} \over {{r_{alpha}}}}} \right)$$ is
Q28.
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Assertion (A) : When radius of a current carrying loop is doubled, its magnetic moment becomes four times.
Reason (R) : The magnetic moment of a current carrying loop is directly proportional to the area of the loop.
Q29.
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Two wires carrying currents I~1~ and I~2~ lie, one slightly above the other, in a horizontal plane as shown in figure. The region of vertically upward strongest magnetic field is
Q30.
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A constant current is flowing through a solenoid. An iron rod is inserted in the solenoid along its axis. Which of the following quantities will not increase?
Q31.
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Two parallel conductors carrying current of 4.0 A and 10.0 A are placed 2.5 cm apart in vacuum. The force per unit length between them is -
Q32.
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The equivalent resistance between A and B of the network shown in figure is
Q33.
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In a dc circuit the direction of current inside the battery and outside the battery respectively are -
Q34.
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If n, e, $$\tau$$ and m have their usual meanings, then the resistance of a wire of length l and cross-sectional area A is given by -
Q35.
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If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a -
Q36.
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**Passage:**
Case Study :
An experiment was set up with the circuit diagram shown in figure. Given that R~1~ = 10 $$\Omega$$, R~2~ = R~3~ = 5 $$\Omega$$, r = 0 $$\Omega$$ and E = 5 V
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The power dissipated in R~1~ is -
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The power dissipated in R~1~ is -
Q37.
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Kirchhoff's first rule $$\Sigma$$I = 0 and second rule $$\Sigma$$IR = $$\Sigma$$E (where the symbols have their usual meanings) are respectively based on -
Q38.
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The electric power consumed by a 220 V $$-$$ 100 W bulb when operated at 110 V is
Q39.
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**Passage:**
Case Study :
An experiment was set up with the circuit diagram shown in figure. Given that R~1~ = 10 $$\Omega$$, R~2~ = R~3~ = 5 $$\Omega$$, r = 0 $$\Omega$$ and E = 5 V
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The current through branch bg is -
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The current through branch bg is -
Q40.
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Two sources of equal emf are connected in series. This combination is, in turn connected to an external resistance R. The internal resistance of two sources are r~1~ and r~2~ (r~2~ > r~1~). If the potential difference across the source of internal resistance r~2~ is zero, then R equals to -
Q41.
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Assertion (A) : Higher the range, lower is the resistance of an ammeter.
Reason (R) : To increase the range of an ammeter additional shunt is added in series to it.
Q42.
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**Passage:**
Case Study :
An experiment was set up with the circuit diagram shown in figure. Given that R~1~ = 10 $$\Omega$$, R~2~ = R~3~ = 5 $$\Omega$$, r = 0 $$\Omega$$ and E = 5 V
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The potential difference across R~3~ is -
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The potential difference across R~3~ is -
Q43.
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A potential difference of 200 V is maintained across a conductor of resistance 100 $$\Omega$$. The number of electrons passing through it in 1s is
Q44.
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**Passage:**
Case Study :
An experiment was set up with the circuit diagram shown in figure. Given that R~1~ = 10 $$\Omega$$, R~2~ = R~3~ = 5 $$\Omega$$, r = 0 $$\Omega$$ and E = 5 V
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The points with the same potential are -
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The points with the same potential are -
Q45.
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A car battery is charged by a 12 V supply, and energy stored in it is 7.20 $$\times$$ 10^(5) J. The charge passed through the battery is -
Q46.
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When an alternating voltage E = E~o~ sin $$\omega$$t is applied to a circuit, a current $$I = {I_o}\sin \left( {\omega t + {\pi \over 2}} \right)$$ flows through it. The average power dissipated in the circuit is
Q47.
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In a circuit the phase difference between the alternating current and the source voltage is $${\pi \over 2}$$. Which of the following cannot be the elements of the circuit?
Q48.
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The voltage across a resistor, an inductor, and a capacitor connected in series to an ac source are 20 V, 15 V and 30 V respectively. The resultant voltage in the circuit is
Q49.
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The rms current in a circuit connected to a 50 Hz ac source is 15 A. The value of the current in the circuit $$\left( {{1 \over {600}}} \right)$$s after the instant the current is zero, is -
Q50.
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The core of a transformer is laminated to reduce the effect of
Q51.
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A 15 $$\Omega$$ resistor, an 80 mH inductor and a capacitor of capacitance C are connected in series with a 50 Hz ac source. If the source voltage and current in the circuit are in phase, then the value of capacitance is
Q52.
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The impedance of a series LCR circuit is -
Q53.
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Assertion (A) : A step-up transformer cannot be used as a step-down transformer.
Reason (R) : A transformer works only in one direction.
Q54.
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A 300 $$\Omega$$ resistor and a capacitor of $$\left( {{{25} \over \pi }} \right)$$ $$\mu$$F are connected in series to a 200 V $$-$$ 50 Hz ac source. The current in the circuit is -
Q55.
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A circuit is connected to an ac source of variable frequency. As the frequency of the source is increased, the current first increases and then decreases. Which of the following combinations of elements is likely to comprise the circuit?