Physics - Electric Charges Fields - Quiz-9

A particle of mass m and carrying charge -q₁ is moving around a charge +q₂ along a circular path of radius r. The period of revolution of the charge -q₁ is:

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$\sqrt{\frac{16 π^{3} ε_{0} {mr}^{3}}{q_{1} q_{2}}}$
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$\sqrt{\frac{8 π^{3} ε_{0} {mr}^{3}}{q_{1} q_{2}}}$
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$\sqrt{\frac{q_{1} q_{2}}{16 π^{3} ε_{0} {mr}^{3}}}$
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zero

Consider three point objects P, Q and R. P and Q repel each other while P and R attract each other. What is the nature of force between Q and R?

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Repulsive force
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Attractive force
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No force
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None of these

The electric field intensity at a point in a vacuum is equal to:

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zero
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the force a proton would experience there.
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the force an electron would experience there.
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the force a unit positive charge would experience there.

A sphere of radius r has an electric charge uniformly distributed in its entire volume. At a distance d from the centre inside the sphere (d<r) the electric field intensity is directly proportional to:

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$\frac{1}{d}$
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$\frac{1}{d^{2}}$
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d
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$d^{2}$

The electric field at a distance 2R from the centre of a uniformly charged non-conducting sphere of radius R is E. The electric field at a distance $\frac{R}{2}$ from the centre will be:

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Zero
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2E
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4E
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16E

In a uniform electric field if a charge is fired in a direction different from the line of the electric field, then the trajectory of the charge will be a:

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straight line
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circle
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parabola
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ellipse

A positively charged pendulum is oscillating in a uniform electric field pointing upwards. Its time period as compared to that when it oscillates without electric field:

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is less.
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is more.
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remains unchanged.
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starts fluctuating.

How many electrons should be removed from a coin of mass 1.6 g so that it may float in an electric field of intensity $10^{9}$ N/C directed upwards?

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$9.8 \times 10^{7}$
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$9.8 \times 10^{5}$
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$9.8 \times 10^{3}$
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$9.8 \times 10^{1}$

ABC is an equilateral triangle. Charges +q are placed at each corner. The electric field intensity at the centroid of the triangle will be:

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$\frac{1}{4 {πε}_{0}} \times \frac{q}{r^{2}}$
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$\frac{1}{4 {πε}_{0}} \times \frac{3 q}{r^{2}}$
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$\frac{1}{4 {πε}_{0}} \times \frac{q}{r}$
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Zero

A charge Q is placed at the centre of a square. If the electric field intensity due to the charges at the corners of the square is E₁ and the intensity at the midpoint of the side of the square is E₂, then the ratio $\frac{E_{1}}{E_{2}}$ will be:

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$\frac{1}{2 \sqrt{2}}$
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$\sqrt{2}$
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$\frac{1}{2}$
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$2$

Point charges, each of magnitude Q, are placed at the three corners of a square as shown in the diagram.

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OC
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OE
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OD
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OB

Two charges e and 3e are placed at a distance r. The distance of the point where the electric field intensity will be zero is:

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$\frac{r}{(1 + \sqrt{3})}$ from 3e charge.
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$\frac{r}{(1 + \sqrt{3})}$ from e charge.
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$\frac{r}{(1 - \sqrt{3})}$ from 3e charge.
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$\frac{r}{1 + \sqrt{\frac{1}{3}}}$ from e charge.

An uncharged sphere of metal is placed in a uniform electric field produced by two oppositely charged plates. The lines of force will appear as:

An electron released on the axis of a positively charged ring at a large distance from the centre will:

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not move.
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do oscillatory motion.
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do SHM.
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do non-periodic motion.

The figure shows electric lines of forces due to charges Q₁ and Q₂. Hence,

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Q₁ and Q₂ both are negative.
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Q₁ and Q₂ both are positive.
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Q₁ > Q₂
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Both (2) and (3)

Electric charges Q, Q and -2Q respectively are placed at the three corners of an equilateral triangle of side a. The magnitude of the electric dipole moment of the system is:

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$\sqrt{2} Qa$
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$\sqrt{3} Qa$
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Qa
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2Qa

An electric dipole placed in a uniform electric field experiences a maximum moment of couple when the dipole is placed:

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against the direction of the field.
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towards the electric field.
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perpendicular to the direction of the field.
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at $135 °$ to the direction of the field.

The force of interaction between two co-axial short electric dipoles whose centres are R distance apart varies as:

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$\frac{1}{R}$
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$\frac{1}{R^{2}}$
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$\frac{1}{R^{3}}$
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$\frac{1}{R^{4}}$

Two charges of $+ 25 \times 10^{- 9}$ coulomb and $- 25 \times 10^{- 9}$ coulomb are placed 6m apart. Find the electric field intensity ratio at points 4 m from the centre of the electric dipole (i) on the axial line (ii) on the equatorial line

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$\frac{1000}{49}$
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$\frac{49}{1000}$
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$\frac{500}{49}$
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$\frac{49}{500}$

The electric force on a point charge situated on the axis of a short dipole is F. If the charge is shifted along the axis to double the distance, the electric force acting will be:

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4F
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$\frac{F}{2}$
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$\frac{F}{4}$
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$\frac{F}{8}$

An electric dipole is placed at an angle $60 °$ with an electric field of strength $4 \times 10^{6}$ N/C. It experiences a torque equal to $8 \sqrt{3}$ Nm. Calculate the charge on the dipole, if the dipole is of length 4 cm.

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$10^{- 1} C$
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$10^{- 2} C$
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$10^{- 3} C$
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$10^{- 4} C$

A charge q is situated at the centre of a cube. The electric flux through one of the faces of the cube is:

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$\frac{q}{ε_{0}}$
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$\frac{q}{3 ε_{0}}$
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$\frac{q}{6 ε_{0}}$
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Zero

A charge Q is placed at the centre of the open end of a cylindrical vessel. The electric flux through the surface of the vessel is:

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$\frac{q}{2 ε_{0}}$
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$\frac{q}{ε_{0}}$
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$\frac{2 q}{ε_{0}}$
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Zero

Total electric flux associated with a unit positive charge in a vacuum is:

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$4 {πε}_{0}$
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$\frac{1}{4 {πε}_{0}}$
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$\frac{1}{ε_{0}}$
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$ε_{0}$

A charged body has an electric flux F associated with it. Now if the body is placed inside a conducting shell, then the electric flux outside the shell is:

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Zero
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Greater than F
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Less than F
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Equal to F

A rectangular surface of sides 10 cm and 15 cm is placed inside a uniform electric field of 25 V/m such that the surface makes an angle of $30 °$ with the direction of the electric field. Find the flux of the electric field through the rectangular force.

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$0.1675 N / m^{2} C$
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$0.1875 {Nm}^{2} / C$
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Zero
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$0.1075 {Nm}^{2} / C$

If an electric field is given by $10 \hat{i} + 3 \hat{j} + 4 \hat{k}$ , calculate the electric flux through a surface of area 10 units lying in the yz plane.

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100 units
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10 units
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30 units
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40 units

There is a uniform electric field of $8 \times 10^{3} \hat{i} N / C$ . What is the net flux (in SI units) of the uniform electric field through a cube of side 0.3 m oriented so that its faces are parallel to the coordinate plane?

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$2 \times 8 \times 10^{3}$
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$0.3 \times 8 \times 10^{3}$
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Zero
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$8 \times 10^{6} \times 6$

A charge Q is kept at the corner of a cube. The electric flux passing through one of those faces not touching that charge is:

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$\frac{Q}{24 ε_{0}}$
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$\frac{Q}{3 ε_{0}}$
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$\frac{Q}{8 ε_{0}}$
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$\frac{Q}{6 ε_{0}}$

The electric field in a region is radially outward and at a point is given by $E = 250 r V / m$ (where r is the distance of the point from origin). Calculate the charge contained in a sphere of radius 20 cm centred at the origin.

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$2.22 \times 10^{- 6} C$
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$2.22 \times 10^{- 8} C$
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$2.22 \times 10^{- 10} C$
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Zero

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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