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Physics M.C.Q (1 Marks)

MODEL PAPER 6 · Gujarat Board (GSEB) STD 12 Science (GSEB - English Medium). 12 questions.

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M.C.Q (1 Marks)

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12 questions · self-marked practice — reveal the answer and mark yourself.

MCQ 11 Mark
The layered lens is made of two kinds of glass. A point source of light is placed on its principal axis. If the reflections from the boundaries between layers are ignored, the lens will form
  • A
    no image at all
  • B
    two images
  • C
    infinite images
  • D
    only one image
Answer
(d) only one image
Explanation: It is like a combination of two Plano – convex lenses. Therefore only one image is formed.
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MCQ 21 Mark
The diode used in the circuit shown in the figure has a constant voltage drop at 0.5 V at all currents and a maximum power rating of 100 milliwatts. What should be the value of the resistor R, connected in series with diode for obtaining maximum current?
Image
  • A
    $20 \Omega$
  • B
    $6.76 \Omega$
  • C
    $5 \Omega$
  • D
    $5.6 \Omega$
Answer
(c) $5 \Omega$
Explanation: Voltage drop across diode, $V _{ d }=0.5 V$
Power rate of diode, $P _{ d }=100 mW=0.1 W$
Resistance of the diode,
$I _{ d }=\frac{V_d}{R_d}=\frac{0.5}{2.5}=0.2 A$
Maximum current through the diode,
$I _{ d }=\frac{V_d}{R_d}=\frac{0.5}{2.5}=0.2 A$
Applied voltage, V = 1.5 V
$R ^{\prime}=\frac{V}{I_d}=\frac{1.5}{0.2}=7.5 \Omega$
Value of the series resistor, $R = R ^{\prime}- R _{ d }=7.5-2.5=5 \Omega$Required total resistance of the circuit,
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MCQ 31 Mark
When a negatively charged conductor is connected to earth
  • A
    Electrons flow from the earth to the conducto
  • B
    Protons flow from the conductor to the earth
  • C
    No charge flow occurs
  • D
    Electrons flow from the conductor to the earth
Answer
(d) Electrons flow from the conductor to the earth
Explanation: After earthing a positively charged conductor electrons flow from earth to conductor and if a negatively charged conductor is earthed then electrons flows from conductor to earth.
Image
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MCQ 41 Mark
Which of the following phenomenon cannot take place with longitudinal waves (e.g., sound waves)?
  • A
    polarisation
  • B
    diffraction
  • C
    reflection
  • D
    interference
Answer
(a) polarisation
Explanation: polarisation
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MCQ 51 Mark
The ratio of magnetic fields due to a small bar magnet in the end on position to the broad side on position is
  • A
    1 : 1
  • B
    1 : 4
  • C
    2 : 1
  • D
    1 : 2
Answer
(c) 2 : 1
Explanation: 2 : 1
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MCQ 61 Mark
Given magnetic field B, area A and length l of a solenoid. The magnetic energy per unit volume is
  • A
    $\frac{1}{2 \mu_0} B^2 A$
  • B
    $\frac{3}{2 \mu_0} B^2 A l$
  • C
    $\frac{1}{2 \mu_0} B^3 A l$
  • D
    $\frac{B^2}{2 \mu_0}$
Answer
(d) $\frac{B^2}{2 \mu_0}$
Explanation: $U=\frac{1}{2 \mu_0} B^2 A l$
$\frac{U}{V}=\frac{B^2}{2 \mu_0}$
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MCQ 71 Mark
A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west in the same direction. The magnetic field at P is:
  • A
    reater or less than at Q, depending upon the strength of the current
  • B
    greater than at Q
  • C
    less than at Q
  • D
    same as at Q
Answer
(d) same as at Q
Explanation: As per Biot Savart Law, Magnetic field at a point is inversely proportional to square of distance from the current carrying conductor. Therefore magnitude of magnetic field is same at both points P and Q, irrespective of their position from the conductor.
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MCQ 81 Mark
A capacitor is charged by a battery. Between the plates, during process of charging:
  • A
    only conduction current exists.
  • B
    only displacement current exists.
  • C
    both displacement current and conduction current exist.
  • D
    no current exists.
Answer
(b) only displacement current exists.
Explanation: only displacement current exists.
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MCQ 91 Mark
A bar magnet is cut into two equal halves parallel to its magnetic axis. The physical quantity that remains unchanged is:
  • A
    moment of inertia
  • B
    pole strength
  • C
    magnetic moment
  • D
    magnitude of magnetisation
Answer
(d) magnitude of magnetisation
Explanation: magnitude of magnetisation
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MCQ 101 Mark
An object approaches a convergent lens from the left of the lens with a uniform speed 5 m/s and stops at the focus. The image
  • A
    moves away from the lens with a uniform acceleration
  • B
    moves away from the lens with a uniform speed 5 m/s
  • C
    moves towards the lens with a non-uniform acceleration
  • D
    moves away from the lens with a nonuniform acceleration
Answer
(d) moves away from the lens with a non-uniform acceleration
Explanation: When an object approaches a lens with uniform speed, its image moves away from the lens to infinity with nonuniform acceleration.
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M.C.Q (1 Marks) - Physics STD 12 Science Questions - Vidyadip