What is the angle between the electric dipole moment and the electric field strength due to it on the equatorial line?
1.
2.
3.
4. None of these
The electrostatic field due to a charged conductor just outside the conductor is:
1. | zero and parallel to the surface at every point inside the conductor. |
2. | zero and is normal to the surface at every point inside the conductor. |
3. | parallel to the surface at every point and zero inside the conductor. |
4. | normal to the surface at every point and zero inside the conductor. |
X and Y are large, parallel conducting plates close to each other. Each face has an area A. X is given a charge Q. Y is without any charge. Point A, B, and C are as shown in the figure. Find the incorrect option.
1. the field at B is
2. the field at B is
3. the fields at A, B and C are of the same magnitude
4. the fields at A and C are of the same magnitude but in opposite directions
Four charges are arranged at the corners of a square ABCD, as shown in the adjoining figure. The force on the charge kept at the centre O is:
1. | Zero | 2. | Along the diagonal AC |
3. | Along the diagonal BD | 4. | Perpendicular to side AB |
Three charges \(4q,Q,\) and \(q\) are in a straight line in the position of \(0,l/2,\) and \(l\) respectively. The resultant force on \(q\) will be zero if \(Q\) equal to:
1. \(-q\)
2. \(-2q\)
3. \(\frac{-q}{2}\)
4. \(4q\)
Force of attraction between two point charges Q and – Q separated by d meter is Fe. When these charges are given to two identical spheres of radius R = 0.3 d whose centres are d meter apart, the force of attraction between them is
1. Greater than Fe
2. Equal to Fe
3. Less than Fe
4. None of the above
When \(10^{19}\) electrons are removed from a neutral metal plate, the electric charge on it is?
1. | \(-1.6\) C | 2. | \(+1.6\) C |
3. | \(10^{19}\) C | 4. | \(10^{-19}\) C |
Three charges are placed at the vertices of an equilateral triangle of side ‘a’ as shown in the following figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is
(1)
(2)
(3) Zero
(4)
Two particles of equal mass \(m\) and charge \(q\) are placed at a distance of \(16~\text{cm}\). They do not experience any net force. The value of \(\frac{q}{m}\) is:
1. \(l\)
2. \(\sqrt{\frac{\pi \varepsilon_0}{G}}\)
3. \(\sqrt{\frac{G}{4\pi \varepsilon_0}}\)
4. \(\sqrt{4\pi \varepsilon_0 G}\)
Two identical conductors of copper and aluminium are placed in an identical electric field. The magnitude of induced charge in the aluminum will be
(1) Zero
(2) Greater than in copper
(3) Equal to that in copper
(4) Less than in copper
\(ABC\) is an equilateral triangle. Charges \(+q\) are placed at each corner. The electric intensity at \(O\) will be:
1. \(\frac{1}{4\pi\epsilon _0}\frac{q}{r^{2}}\)
2. \(\frac{1}{4\pi\epsilon _0}\frac{q}{r^{}}\)
3. zero
4. \(\frac{1}{4\pi\epsilon _0}\frac{3q}{r^{2}}\)
A charge particle is free to move in an electric field. It will travel
(1) Always along a line of force
(2) Along a line of force, if its initial velocity is zero
(3) Along a line of force, if it has some initial velocity in the direction of an acute angle with the line of force
(4) None of the above
An uncharged sphere of metal is placed in between two charged plates as shown. The lines of force look like
(1) A
(2) B
(3) C
(4) D
An electron enters an electric field with its velocity in the direction of the electric lines of force. Then:
1. | the path of the electron will be a circle. | 2. | the path of the electron will be a parabola. |
3. | the velocity of the electron will decrease. | 4. | the velocity of the electron will increase. |
The dimension of (1/2) : permittivity of free space; E: electric field) is
(1) MLT–1
(2) ML2L–2
(3) ML–1T–2
(4) ML2T–1
An electron having charge \(e\) and mass \(m\) is moving in a uniform electric field \(E.\) Its acceleration will be:
1. \(\frac{e^2}{m}\)
2. \(\frac{E^2e}{m}\)
3. \(\frac{eE}{m}\)
4. \(\frac{mE}{e}\)
A pendulum bob of mass and carrying a charge is at rest in a horizontal uniform electric field of 20000 V/m. The tension in the thread of the pendulum is
(1)
(2)
(3)
(4)
A charged ball B hangs from a silk thread S, which makes an angle θ with a large charged conducting sheet P, as shown in the figure. The surface charge density σ of the sheet is proportional to:
1. sin θ
2. tan θ
3. cos θ
4. cot θ
Two infinitely long parallel conducting plates having surface charge densities +σ and –σ respectively, are separated by a small distance. The medium between the plates is a vacuum. If ε0 is the dielectric permittivity of vacuum, then the electric field in the region between the plates is
(1)
(2)
(3)
(4)
Four-point +ve charges of the same magnitude (Q) are placed at four corners of a rigid square frame as shown in the figure. The plane of the frame is perpendicular to Z-axis. If a –ve point charge is placed at a distance z away from the above frame (z<<L) then
1. – ve charge oscillates along the Z-axis.
2. It moves away from the frame.
3. It moves slowly towards the frame and stays in the plane of the frame.
4. It passes through the frame only once.
A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by
(1)
(2)
(3)
(4) Zero
An electric charge q is placed at the centre of a cube of side a. The electric flux on one of its faces will be:
(1)
(2)
(3)
(4)
Total electric flux coming out of a unit positive charge put in air is
(1)
(2)
(3)
(4)
A cube of side l is placed in a uniform field E, where . The net electric flux through the cube is
(1) Zero
(2) l2E
(3) 4l2E
(4) 6l2E
Shown below is a distribution of charges. The flux of electric field due to these charges through the surface S is
(1)
(2)
(3)
(4) Zero
The electric flux for Gaussian surface A that encloses the charged particles in free space is (given q1 = –14 nC, q2 = 78.85 nC, q3 = – 56 nC)
(1) 103 Nm2 C–1
(2) 103 CN-1 m–2
(3) 6.32 × 103 Nm2 C–1
(4) 6.32 × 103 CN-1 m–2
The electric intensity due to an infinite cylinder of radius R and having charge q per unit length at a distance r(r > R) from its axis is
(1) Directly proportional to r2
(2) Directly proportional to r3
(3) Inversely proportional to r
(4) Inversely proportional to r2
A positively charged ball hangs from a silk thread. We put a positive test charge q0 at a point and measure F/q0, then it can be predicted that the electric field strength E
(1) > F/q0
(2) = F/q0
(3) < F/q0
(4) Cannot be estimated
A point charge q is placed at a distance a/2 directly above the centre of a square of side a. The electric flux through the square (i.e. one face) is:
1.
2.
3.
4.
The charge on 500 cc of water due to protons will be:
1. 6.0 × 1027 C
2. 2.67 × 107 C
3. 6 × 1023 C
4. 1.67 × 1023 C
Charge q is uniformly distributed over a thin half-ring of radius R. The electric field at the centre of the ring is
(1)
(2)
(3)
(4)
An electric dipole is situated in an electric field of uniform intensity E whose dipole moment is p and moment of inertia is I. If the dipole is displaced slightly from the equilibrium position, then the angular frequency of its oscillations is?
1.
2.
3.
4.
Two-point charges +q and –q are held fixed at (–d, 0) and (d, 0) respectively of a (x, y) coordinate system. Then
(1) E at all points on the y-axis is along
(2) The electric field at all points on the x-axis has the same direction
(3) Dipole moment is 2qd directed along
(4) Work has to be done in bringing a test charge from infinity to the origin
The electric field due to a uniformly charged solid sphere of radius R as a function of the distance from its centre is represented graphically by -
(1) (2)
(3) (4)
Suppose the charge of a proton and an electron differ slightly. One of them is \(\text- e\) and the other is \((e+\Delta e)\). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance \(d\) (much greater than atomic size) apart is zero, then \(\Delta e\)
1. \(10^{-20}~\text{C}\)
2. \(10^{-23}~\text{C}\)
3. \(10^{-37}~\text{C}\)
4. \(10^{-47}~\text{C}\)
An electric dipole is place at an angle of \(30^{\circ}\) with an electric field intensity \(2\times10^{5}~\text{N/C}\). It experiences a torque equal to \(4~\text{Nm}\). The charge on the dipole, if the dipole length is \(2~\text{cm}\), is:
1. | \(8~\text{mC}\) | 2. | \(2~\text{mC}\) |
3. | \(5~\text{mC}\) | 4. | \(7~\mu\text{C}\) |
Two identical charged spheres suspended from a common point by two massless strings of lengths l are initially at a distance d(d < < l) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity v. Then, v varies as a function of the distance x between the sphere, as:
(a) \(v \propto x\)
(b) \(v \propto x^{\frac{-1}{2}}\)
(c) \(v \propto x^{-1}\)
(d) \(v \propto x^{\frac{1}{2}}\)
The electric field in a certain region is acting radially outward and is given by E=Ar. A charge contained in a sphere of radius 'a' centered at the origin of the field will be given by
1.
2.
3.
4.
An electric dipole of moment p is placed in an electric field of intensity E. The dipole acquires a position such that the axis of the dipole makes an angle with the direction of the field. Assuming that the potential energy of the dipole to be zero when , the torque and the potential energy of the dipole will respectively be
1.
2.
3.
4.
What is the flux through a cube of side 'a' if a point charge q is at one of its corners?
1.
2.
3.
4.
A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will
1. be reduced to half
2. remain the same
3. be doubled
4. increase four times
Two positive ions, each carrying a charge q, are separated by a distance d. If F is the force of repulsion between the ions, the number of electrons missing from each ion will be (e being the charge on an electron)
1. 2.
3. 4.
A surface of side L metre in the plane of the paper is placed in a uniform electric field E(volt/m) acting along the same plane at an angle with the horizontal side of the square as shown in figure. The electric flux linked to the surface in unit of V-m, is
(1) EL2
(2) EL2cos
(3) EL2sin
(4) 0
The electric field at a distance from the centre of a charged conducting spherical shell of radius R is E. The electric field at a distance from the centre of the sphere is
1. 2.
3. 4.
A thin conducting ring of radius R is given a charge +Q. The electric field at the centre O of the ring due to the charge on the part AKB of the ring is E. The electric field at the centre due to the charge on the part ACDB of the ring is
(1) 3E along KO
(2) E along OK
(3) E along KO
(4) 3E along OK