1638 + Interview Questions in ELECTROSTATICS IN GENERAL AWARENESS Page 26 InterviewSolution

1251.	The electric intensity in air at a point 20 cm from a point charge Q coulombs is 4.5 × 105 N/ C.The magnitude of Q is(A) 20 µC (B) 200 µC (C) 10 µC (D) 2 µC
Answer» Correct option is: (D) 2 µC

Discussion

1252.	An electric dipole of length 4 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of 4√3 Nm. Calculate the potential energy of the dipole, if it has charge ±8 nC
Answer» Torque, t = pE sin q 4√3 = pE sin 60° 4√3 = pE x √3/2 ⇒ pE = 8 Now, potential energy, U = -pE cos θ = -8 cos 60° = -8 x 1/2 = -4 J

1252.

An electric dipole of length 4 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of 4√3 Nm. Calculate the potential energy of the dipole, if it has charge ±8 nC

Answer»

Torque, t = pE sin q

4√3 = pE sin 60°

4√3 = pE x √3/2

⇒ pE = 8

Now, potential energy,

U = -pE cos θ = -8 cos 60°

= -8 x 1/2 = -4 J

Discussion

1253.	An electric dipole is placed in an uniform electric field with the dipole axis making an angle `theta` with the direction of the electric field. The orientation of the dipole for stable equilibrium isA. `(pi)/(6)`B. `(pi)/(3)`C. 0D. `(pi)/(2)`
Answer» Correct Answer - C

Discussion

1254.	Figure shows electric field lines in which an electric dipole p is placed as shown. Which of the following statements is correct ? A. The dipole will not experience any forceB. The dipole will experience a force towards rightC. The dipole will experience a force towards leftD. The dipole will experience of force upwards
Answer» Correct Answer - C

Discussion

1255.	A hollow cylinder has a charge `qC` within it. If `phi` is the electric flux in unit of voltmeter associated with the curved surface `B` the flux linked with the plance surface `A` in unit of voltmeter will be A. `(1)/(2) ((q)/(in_(0)) - phi)`B. `(q)/(2 in_(0))`C. `(phi)/(3)`D. `(q)/(in_(0)) - phi`
Answer» Correct Answer - 1 `phi_(A) + phi_(C ) + phi_(B) = (q_(in))/(in_(0))` `phi_(A) = phi_(C ) , q_(in) = q , phi_(B) = phi` `2 phi_(A) + phi = (q)/(in_(0))` `phi_(A) = (1)/(2) ((q)/(in_(0)) -phi)`

Discussion

1256.	A hollow cylinder has a charge `qC` within it. If `phi` is the electric flux in unit of voltmeter associated with the curved surface `B` the flux linked with the plance surface `A` in unit of voltmeter will be A. `(1)/(2) ((q)/(epsilon_(0))-phi)`B. `(q)/(2 epsilon_(0))`C. `(phi)/(3)`D. `(q)/(epsilon_(0))-phi`
Answer» Correct Answer - A

Discussion

1257.	Consider a uniform spherical charge distribution of radius `R_(1)` centred at the origin `O`. In this distribution a spherical cavity of radius `R_(2)`, centred at `P` with distance `OP = a = R_(1) - R_(2)` (fig) is made.If the electric field inside the cavity at position `vec(r )`, then the correct statement is A. `vec(E)` is uniform, its magnitude is independent of `R_(2)` but its direction depends on `vec(r)`B. `vec(E)` is uniform, its magnitude depends on `R_(2)` and its direction depends on `vec(r)`C. `vec(E)` is uniform, its magnitude is independent of a but its direction depends on `vec(a)`D. `vec(E)` uniform, and both its magnitude and direction depends on `vec(a)`
Answer» Correct Answer - D

Discussion

1258.	The electrostatic energy stored in the 1 litre volume of air when it is placed in uniform electric field of intensity `10^(3)V//m` isA. `44.25xx10^(-9) J`B. `4.425xx10^(-9) J`C. `44.25xx10^(-6) J`D. `44.25xx10^(-5) J`
Answer» Correct Answer - B Energy = `1/2in_(0)kE^(2)xx"volume"` `=(8.85xx10^(-12)xx1xx10^(6)xx10^(-3))/2` `=4.425xx10^(-9)J`

Discussion

1259.	What is the charge on a body from which one million electrons are removed?
Answer» Here, `n = 10^(6), e=1.6xx10^(-19)C` As a elctronics are removed charge acquired is positive `q=n e=10^(6)xx1.6xx10^(-13)C`

Discussion

1260.	A conducting sphere of radius 5 cm has an unknown charge. The electric field at 10 cm from the centre of the sphere is `1.8xx10^(3)NC^(-1)` and points radially inward. What is the net charge on the sphere?A. `1.8nC`B. `2nC`C. `1nC`D. `1.5nC`
Answer» Correct Answer - B For a conducting charged sphere, the electric field outside the sphere, `E=(1)/(4pi epsilon_(0))(Q)/(r^(2))` `1.8xx10^(3)=9xx10^(9)xx(Q)/((0.1)^(2))` The net charge on the sphere `Q=(1.8xx10^(3)xx10^(-2))/(9xx10^(9))` `=2xx10^(-9)C=2nC`

Discussion

1261.	Is a charge of `(5.8xx10^(-18))C` possible?
Answer» From `q = n e, n = (q)/(e) = (5.8xx10^(-18))/(1.6xx10^(-19)) = 36.25` As n is not an interger, this value of charge is not possible.

Discussion

1262.	When your friend chews a winter green life saver in a dark room, you see a faint flash of blue light from his mouth. How?
Answer» This display of light is often called sparking. It occurs due to electric discharge of the electrostatic changes produced in chewing the winter green life saver.

Discussion

1263.	What is the magnitude of a point charge due to which the electric field `30cm` away the magnitude `2`? `[1//4 pi epsilon_(0)=9xx10^(9)Nm^(2)//C^(2)]`A. `2 xx 10^(-11) C`B. `3 xx 10^(-11) C`C. `5 xx 10^(-11) C`D. `9 xx 10^(-11) C`
Answer» Correct Answer - A

Discussion

1264.	The outward pull on a metal plate of area `0.01m^(2)` having a charge density of `50muC//m^(2)` isA. 1.4 NB. 2.4 NC. 0.4 ND. 1.8 N
Answer» Correct Answer - A `F=(sigma^(2)dS)/(2epsi_(0)k)=((50xx10^(-6))^(2)xx0.01)/(2xx8.85xx10^(-12)xx0.01)=1.4N.`

Discussion

1265.	For a dipole `q= 2xx10^(-6)C` and `d= 0.01m`. Calculate the maximum torque for this dipole if `E= 5xx10^(5)N//C`A. `1 xx 10^(-3) N - m^(-1)`B. `10 xx 10^(-3) N - m^(-1)`C. `10 xx 10^(-3) N - m`D. `1 xx 10^(2) N - m^(2)`
Answer» Correct Answer - C

Discussion

1266.	The electric field at a distance `3R//2` from the centre of a charge conducting spherical shell of radius `R` is `E`. The electric field at a distance `R//2` from the centre of the sphere isA. ZeroB. `E`C. `(E )/(2)`D. `(E )/(3)`
Answer» Correct Answer - 1

Discussion

1267.	Suppose in an insulating medium, having di-electric constant k= 1, volume density of positive charge varies with y-coordinate according to law `rho = ay`. A particle of mass m having positive charge q is placed in the medium at point A `(0,y_(0))`J and projected with velocity `vecv = v_(0)hati` as shown in figure. Neglecting gravity and frictional resistance of the medium and assuming electric field strength to be zero at y = 0, calculate slope of trajectory of the particle as a function of y :
Answer» Correct Answer - `[sqrt((qa)/(3mepsi_(0)v_(0)^(2))(y^(3)-y_(0)^(3)))]`

Discussion

1268.	A charge `Q` is placed at the centre of a spherical conducting shell. Choose the correct option.A. Only `-Q` will appear on its inner surfaceB. Only `+Q` will appear on its outer surfaceC. A charge `-Q` will appear on its surface and `+Q` on its outer surfaceD. A charge `+Q` will appear on its inner surface and `-Q` on its outer surface
Answer» Correct Answer - 3

Discussion

1269.	A positive charge `Q` is placed at the centre `O` of a thin metalic spherical shell. Select the correct statements from the following: (i) The electric field at any point outside the shell is zero (ii) The electrostatic potential at any point outside the shell is `(Q)/(4 pi epsilon_(0) r)` , where `r` is the distance of the point from `O` (iii) The outer surface of the spherical shell is an equipotential surface (iv) The electric field at any point inside the shell , other than `O` , is zeroA. `(i),(ii)`B. `(ii),(iii)`C. `(i),(iv)`D. all
Answer» Correct Answer - 2

Discussion

1270.	In an insulating medium (dielectric constant =1) the charge density varies with y Co-ordinate as `rho=by`, where b is a positive constant.t he electric field is zero at y=0 and everywhere else it is along y direction. Calculate the electric field as a function of y.
Answer» Correct Answer - `E=(by^(2))/(2epsilon_(0))`

Discussion

1271.	An electric dipole is fixed at the origin of coordinates. Its moment is directed in the positive `x`- direction. A positive charge is moved from the point `(r,0)` to the point `(-r,0)` by an external agent. In this process, the work done by the agent isA. positive and inversely proportional to `r`B. positive and inversely proportional to `r^(2)`C. negative and inversely proportional to `r`D. negatie and inversely proportional to `r^(2)`
Answer» Correct Answer - D

Discussion

1272.	The `500 muF` capacitor is charged at a steady rate of `100 mu C//s`. The potential difference across the capacitor will be 10 V after an interval ofA. 5 sB. 10 sC. 50 sD. 100 s
Answer» Correct Answer - C Charge, `Q=CV=500muFxx10V=5xx10^(-3)C` Now, `Q=qt" to "t=(Q)/(q)` or Time taken to raise the potential difference `t=(5xx10^(-3))/(100xx10^(-6))=(1)/(20)xx1000s=50s`

Discussion

1273.	With three 6 μF capacitors, which of the capacitance values are available to you ? (A) 2 μF and 18 μF (B) 2 μF, 9 μF, 12 μF and 18 μF (C) 2 μF, 9 μF and 18 μF (D) 2 μF, 6 μF, 9 μF, 12 μF and 18 μF
Answer» (D) 2 μF, 6 μF, 9 μF, 12 μF and 18 μF

Discussion

1274.	Two capacitors each of capacitance 4 μF are connected in series, and a third capacitor of capacitance 4 μF is connected in parallel with the combination. Then, the equivalent capacitance of the arrangement is (A) 12 μF (B) 8 μF (C) 6 μF (D) 2.65 μF
Answer» Correct option is (C) 6 μF

Discussion

1275.	A condenser of capacity `C` is charged to a potential difference of `V_(1)`. The plates of the condenser are then connected to an ideal inductor of inductance `L`. The current through the inductor wehnn the potential difference across the condenser reduces to `V_(2)` isA. `((C(V_(1) - V_(2))^(2))/(L))^(1/2)`B. `(C(V_(1)^(2) - V_(2)^(2)))/(L)`C. `(C(V_(1)^(2) + V_(2)^(2)))/(L)`D. `((C(V_(1)^(2) - V_(2)^(2)))/(L))^(1/2)`
Answer» Correct Answer - D Here, `q_(0) = CV_(1)` and `q = CV_(2)` When a charged capacitor is connected to ideal inductor, the discharge of capacitor is oscillatory. The chagre on capacitor at an instant `t` is given by, `q = q_(0) sin omega` where `omega = (1)/(sqrt(LC))`. Therefore, `sin omega = (q)/(q_(0)) = (CV_(2))/(CV_(1)) = (V_(1))/(V_(1))` Current through inductor is `I = (dq)/(dr) = (d)/(dt) (q_(0) sin omega t) = q_(0) omega cos omega` `= q_(0) [1 - sin^(2) omega t]^(1//2)` `= CV_(1) xx (1)/(sqrt(LC)) [1 - ((V_(2))/(V_(1)))^(2)]^(1//2)` `= [(C(V_(1)^(2) - V_(2)^(2)))/(L)]^(1//2)`

Discussion

1276.	Can the potential function have a maximum or minimum is free space ?
Answer» No, The potential function cannnot have a maximum or minimum in free space. This iss because is that event, `E = (dV)/(dr) = Zero`.

Discussion

1277.	Find out the potentail difference across the plates of `1 mu F` capacitors in Fig.
Answer» Correct Answer - `3.82 V` In Fig. `C_(P_(1)) = 3+6 = 9 muF` `(1)/(C_(S_(1))) = (1)/(4) + (1)/(9) = (13)/(36) C_(S_(1)) = (36)/(13) muF` `C_(P_(2)) = (36)/(13) + 12 = (36+156)/(13) = (192)/(13) muF` `(1)/(C_(s)) = (1)/(2) + (1)/(2) + (13)/(192) = (192+96+13)/(192) = (301)/(192)` `C_(s) = (192)/(301) muF Q = C_(s) V = (192)/(301) xx 6 muC` `V_(1) = (Q)/(C_(1)) = (192xx6)/(301xx1) = 3.82` volt

Discussion

1278.	A uniform field of `2 kN//C` is the x direction. A point charge `= 3 mu C` initially at rest at the origin is released. What is K.E. of this charge at x = 4m ? Also, calculate `V (4m) - V (0)`.
Answer» Correct Answer - 24xx10^(17) Vm^(-1) ; 4.5xx10^(21) Vm^(-1)` From `E = - (dV)/(dr)`, `dV = -E (dr) = -2xx10^(3) (4) = -8xx10^(3) V` Gain in K.E. = Loss in P.E. `= q (dV) = 3xx10^(3) (8xx10^(3)) = 24xx10^(-3)J`

Discussion

1279.	Do free electrons travel to region of higher potential or lower potentail ?
Answer» As free electrons are negatively charged, they would move to regions of higher potential.

Discussion

1280.	If the potentail in the region of space around the point `(-1m,2m,3m)` is given by `V = (10 x^(2) + 5 y^(2) - 3 z^(2))`, calculate the three components of electric field at this point.
Answer» Correct Answer - `E_(x) = 20 V m^(-1) ; E_(y) = -20 V m^(-1) ; E_(z) = 18 V m^(-1)` Here `x = -1 m, y = 2 m, z = 3m` `E_(x) = (-del V)/(del x) = (-del)/(del x) (10 x^(2) + 5 y^(2) - 3z^(2))` `= -20x = -20 (-1) = +- 20 Vm^(-1)` `E_(y) = (-del V)/(del z) = - (del)/(del y) (10 x^(2) + 5 y^(2) - 3z^(2))` `= -10y = -10(2) = -20 V m^(-1)` `E_(z) = (-del V)/(del z) = -(del)/(del z) (10 x^(2) + 5 y^(2) - 3z^(2))` `= 6z = 6 (3) = 18 Vm^(-1)`

Discussion

1281.	Two charges of magnitude `5 nC and -2 nC` are placed at points (2cm,0,0) and (x cm,0,0) in a region of space. Where there is no other external field. If the electrostatic potential energy of the system is `-0.5 muJ`. What is the value of x ?
Answer» Correct Answer - x = 4cm `U = (1)/(4pi in_(0)) (q_(1) q_(2))/(r )` `-5xx10^(-6) = (9xx10^(9)xx5xx10^(-9)xx(-2)xx10^(-9))/((x-2)xx10^(-2))` `x - 2 = (9xx10^(9)xx5xx10^(-9)xx -2xx10^(-9))/(-0.5xx10^(-6)xx10^(-2))` On solving, `x = 4cm`

Discussion

1282.	A charged particle q is shot from a large distance twoards another charged particle Q which is fixed, with speed v. It approaches Q up to as closed distance r and then returns. If q were given a speed 2v, the distasnce of approach would be A. rB. `2r`C. `r//2`D. `r//4`
Answer» Correct Answer - D `U_i+k_i=U_f+K_f` `0+1/2mv^2=1/4piepsilon_0.(Qq)/r+or rprop1/v^2` If v is doubled, the minimum distance r will remain `1/4` the.

Discussion

1283.	On moving a charge of ` 20 ` coulomb by ` 2 cm`, ` 2J` of work is done , the potential difference between the points is .A. ` 0. 1 V`B. ` 8 V`C. ` 2 V`D. ` 0. 5 V`
Answer» Correct Answer - A Potential difference between two points in a eelc - tric field is , `V_A - V_B= W/( q_0)` where , `W` is work by moving charge `q_0` from point `A` to `B` . So, `V_A - V_B =2/(2 0)` (Here : `W =2 2 J, q_0 = 20 C`) `=0. 1 V` .

Discussion

1284.	A `2 mu F` condenser is charged upto 200 volt and then battery is removed. On combining this with another uncharged condenser in parallel, the potential difference is found to be 40 volt. Find the capacity of second condenser (in `mu F`)
Answer» Correct Answer - 8

Discussion

1285.	In a uniform electric field , equipotential surface must (i) be plane surfaces (ii) be normal to the direction to the filed (iii) be spaced such that surfaces having equal difference in potential are separated by equal distances (iv) have decreasing potentials in the direction of fieldA. be plane surfacesB. be normal to the direction of the fieldC. be sapced such that surfaces having equal differences in potential are separated by equal distancesD. have decreasing potentials in the direction of the field
Answer» Correct Answer - A::C::D

Discussion

1286.	When thee dipole is aligned parallel to the field, its electric potential energy is …………
Answer» When thee dipole is aligned parallel to the field, its electric potential energy is u = -PE

Discussion

1287.	A molecule with a dipole moment `p` is placed in an electric field of strength `E`. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated to be anti-parallel to the field, the work required to be done by an external agency isA. `-2 pE`B. `-pE`C. `pE`D. `2pE`
Answer» Correct Answer - D

Discussion

1288.	A parallel plate capacitor has a capacity c. If a medium of dielectric constant K is introduced between plates, the capacity of capacitor becomesA. `C/K`B. `C/K^(2)`C. `M^(2)C`D. KC
Answer» Correct Answer - D `C_(m)=C_("air")k=Ck`

Discussion

1289.	A parallel -plate capacitor is connected to a cell. A sheet of dielectric and a metal sheet are now introduced between the plates of the capacitor, parallel to these plates. The electric intensity between the positive plate of the capcitor and the metal sheet is `E_(2)`, and between the metal sheet and the negatilve plate is `E_(3)`. ThenA. `E_(1)=E_(2)=E_(3)`B. `E_(1)=E_(2)!=E_(3)`C. `E_(1)!=E_(2)=E_(3)`D. `E_(1)!=E_(2)!=E_(3)`
Answer» Correct Answer - A

Discussion

1290.	The energy required to charge a parallel plate condenser of plate separtion `d` and plate area of cross-section `A` such that the unifom field between the plates is `E` isA. `(1)/(2)(epsilon_(0)E^(2))/(Ad)`B. `(epsilon_(0)E^(2))/(Ad)`C. `epsilon_(0)E^(2)Ad`D. `(1)/(2)(epsilon_(0)E^(2))/(Ad)`
Answer» Correct Answer - C

Discussion

1291.	The energy required to charge a parallel plate condenser of plate separtion `d` and plate area of cross-section `A` such that the unifom field between the plates is `E` isA. `(1)/(2)epsilon_(0)E^(2)//Ad`B. `epsilon_(0)E^(2)//Ad`C. `epsilon_(0)E^(2)Ad`D. `(1)/(2)epsilon_(0)E^(2)Ad`
Answer» Correct Answer - C Energy given by the cell, `E=CV^(2)` Here, C = capacitiance of condenser `=(Aepsilon_(0))/(d)` V = potential across the plates = Ed Therefore, `E=((Aepsilon_(0))/(d))(Ed)^(2)=Aepsilon_(0)E^(2)d`

Discussion

1292.	When an electric dipole P `vecv` is placed in a uniform electric field `vecE` then at what angle between `vecP` and `vecE` the value of torque will be maximaA. `90^(@)`B. `0^(@)`C. `180^(@)`D. `45^(@)`
Answer» Correct Answer - A

Discussion

1293.	An electric dipole of moment `vecp` is placed normal to the lines of force of electric intensity `vecE`, then the work done in deflecting it through an angle of `180^(@)` isA. `Pe`B. `+2pE`C. `-2pE`D. Zero
Answer» Correct Answer - 4 `W_(1 rarr 2) = p E (cos theta_(1) - cos theta_(2)) = p E [ cos 0 - cos 270^(@)]` `= 0`

Discussion

1294.	A parallel plate capacitor with air inbetween the paltes has a capacitance of 8 pF. The separation between the plates is now reduced by half and the space between them is filled with a medium of dielectric constant 5. Calculate the new value of capacitance.
Answer» `C_(0) = (in_(0) A)/(d) = 8 pF` `C = K. (in_(0) A)/(d//2) = 2 KC_(0)` `= 2xx5xx8 pF` = 80 pF

Discussion

1295.	Two infinitely large plane thin parallel sheets having surface charge densities σ1 and σ2 (σ1 >σ2) are shown in the figure. Write the magnitudes and directions of the net fields in the regions marked II and III.
Answer» (i) Net electric field in region II = 1/2ε₀ (σ₁ -σ₂) Direction of electric field in from sheet A to sheet B. (ii) Net electric field in region III = 1/2ε₀ (σ₁ -σ₂) Direction is away from the two sheets i.e. towards right side.

1295.

Two infinitely large plane thin parallel sheets having surface charge densities σ1 and σ2 (σ1 >σ2) are shown in the figure. Write the magnitudes and directions of the net fields in the regions marked II and III.

Answer»

(i) Net electric field in region II = 1/2ε₀ (σ₁ -σ₂)

Direction of electric field in from sheet A to sheet B.

(ii) Net electric field in region III = 1/2ε₀ (σ₁ -σ₂)

Direction is away from the two sheets i.e. towards right side.

Discussion

1296.	Electric intensity at a point just outside a charged conductor of any shape isA. `sigma/(in_(0)K)`B. `sigma/(2in_(0)K)`C. `(2sigma)/(inK)`D. `(sigma^(2))/(2inK)`
Answer» Correct Answer - A

Discussion

1297.	The number of electrons to be put on a spherical conductor of radius `0.1m` to produce an electric field of `0.036N//C` just above its surface isA. `2.4xx10^(5)`B. `2.5xx10^(5)`C. `2.6xx10^(5)`D. `2.7xx10^(5)`
Answer» Correct Answer - B The electric field at the surface of conductor `E=1/(4piepsilon_(0)).q/(R^(2))` Charge `q=4piepsilon_(0)R^(2)E` From q=ne `n e=4piepsilon_(0) R^(2)E` `n=(4piepsilon_(0)R^(2)E)/e` Here `4piepsilon_(0)=1/(9xx10^(9))` column `b^(2)//N-m^(2)` R=0.1 m E=0.036 N/C `e=1.6xx10^(-19)` coulomb So, `n=1/(9xx10^(9))xx((0.1)^(2)xx(0.036))/(1.6xx10^(-19))=2.5 xx10^(5)`

Discussion

1298.	The capacitance of an isolated spherical conductor of radius R in vacuum is (A) not defined (B) zero (C) 4πε0R (D) infinite.
Answer» Correct option is (C) 4πε₀R

Discussion

1299.	Capacitance (in F) of a spherical conductor with radius 1m isA. (a) `1.1xx10^-10`B. (b) `10^-6`C. (c) `9xx10^-9`D. (d) `10^-3`
Answer» Correct Answer - A For an isolated sphere, the capacitance is given by `C=4pi in_0 r=(1)/(9xx10^9)xx1=1.1xx10^-10F`

Discussion

1300.	The capacitance of the earth, viewed as a spherical conductor of radius 6408 km isA. `980muF`B. `1424muF`C. `712muF`D. `600muF`
Answer» Correct Answer - C C = ? R = 6408 km `C=4piin_(0)kR` `=(6408xx10^(3))/(9xx10^(9))=712xx10^(-6)F=712muF`

Discussion

Explore topic-wise InterviewSolutions in .

The electric intensity in air at a point 20 cm from a point charge Q coulombs is 4.5 × 105 N/ C.The magnitude of Q is(A) 20 µC (B) 200 µC (C) 10 µC (D) 2 µC

An electric dipole of length 4 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of 4√3 Nm. Calculate the potential energy of the dipole, if it has charge ±8 nC

An electric dipole is placed in an uniform electric field with the dipole axis making an angle `theta` with the direction of the electric field. The orientation of the dipole for stable equilibrium isA. `(pi)/(6)`B. `(pi)/(3)`C. 0D. `(pi)/(2)`

A hollow cylinder has a charge `qC` within it. If `phi` is the electric flux in unit of voltmeter associated with the curved surface `B` the flux linked with the plance surface `A` in unit of voltmeter will be A. `(1)/(2) ((q)/(in_(0)) - phi)`B. `(q)/(2 in_(0))`C. `(phi)/(3)`D. `(q)/(in_(0)) - phi`

The electrostatic energy stored in the 1 litre volume of air when it is placed in uniform electric field of intensity `10^(3)V//m` isA. `44.25xx10^(-9) J`B. `4.425xx10^(-9) J`C. `44.25xx10^(-6) J`D. `44.25xx10^(-5) J`

What is the charge on a body from which one million electrons are removed?

A conducting sphere of radius 5 cm has an unknown charge. The electric field at 10 cm from the centre of the sphere is `1.8xx10^(3)NC^(-1)` and points radially inward. What is the net charge on the sphere?A. `1.8nC`B. `2nC`C. `1nC`D. `1.5nC`

Is a charge of `(5.8xx10^(-18))C` possible?

When your friend chews a winter green life saver in a dark room, you see a faint flash of blue light from his mouth. How?

What is the magnitude of a point charge due to which the electric field `30cm` away the magnitude `2`? `[1//4 pi epsilon_(0)=9xx10^(9)Nm^(2)//C^(2)]`A. `2 xx 10^(-11) C`B. `3 xx 10^(-11) C`C. `5 xx 10^(-11) C`D. `9 xx 10^(-11) C`

The outward pull on a metal plate of area `0.01m^(2)` having a charge density of `50muC//m^(2)` isA. 1.4 NB. 2.4 NC. 0.4 ND. 1.8 N

For a dipole `q= 2xx10^(-6)C` and `d= 0.01m`. Calculate the maximum torque for this dipole if `E= 5xx10^(5)N//C`A. `1 xx 10^(-3) N - m^(-1)`B. `10 xx 10^(-3) N - m^(-1)`C. `10 xx 10^(-3) N - m`D. `1 xx 10^(2) N - m^(2)`

The electric field at a distance `3R//2` from the centre of a charge conducting spherical shell of radius `R` is `E`. The electric field at a distance `R//2` from the centre of the sphere isA. ZeroB. `E`C. `(E )/(2)`D. `(E )/(3)`

In an insulating medium (dielectric constant =1) the charge density varies with y Co-ordinate as `rho=by`, where b is a positive constant.t he electric field is zero at y=0 and everywhere else it is along y direction. Calculate the electric field as a function of y.

The `500 muF` capacitor is charged at a steady rate of `100 mu C//s`. The potential difference across the capacitor will be 10 V after an interval ofA. 5 sB. 10 sC. 50 sD. 100 s

With three 6 μF capacitors, which of the capacitance values are available to you ? (A) 2 μF and 18 μF (B) 2 μF, 9 μF, 12 μF and 18 μF (C) 2 μF, 9 μF and 18 μF (D) 2 μF, 6 μF, 9 μF, 12 μF and 18 μF

Two capacitors each of capacitance 4 μF are connected in series, and a third capacitor of capacitance 4 μF is connected in parallel with the combination. Then, the equivalent capacitance of the arrangement is (A) 12 μF (B) 8 μF (C) 6 μF (D) 2.65 μF

Can the potential function have a maximum or minimum is free space ?

Find out the potentail difference across the plates of `1 mu F` capacitors in Fig.

A uniform field of `2 kN//C` is the x direction. A point charge `= 3 mu C` initially at rest at the origin is released. What is K.E. of this charge at x = 4m ? Also, calculate `V (4m) - V (0)`.

Do free electrons travel to region of higher potential or lower potentail ?

If the potentail in the region of space around the point `(-1m,2m,3m)` is given by `V = (10 x^(2) + 5 y^(2) - 3 z^(2))`, calculate the three components of electric field at this point.

Two charges of magnitude `5 nC and -2 nC` are placed at points (2cm,0,0) and (x cm,0,0) in a region of space. Where there is no other external field. If the electrostatic potential energy of the system is `-0.5 muJ`. What is the value of x ?

A charged particle q is shot from a large distance twoards another charged particle Q which is fixed, with speed v. It approaches Q up to as closed distance r and then returns. If q were given a speed 2v, the distasnce of approach would be A. rB. `2r`C. `r//2`D. `r//4`

On moving a charge of ` 20 ` coulomb by ` 2 cm`, ` 2J` of work is done , the potential difference between the points is .A. ` 0. 1 V`B. ` 8 V`C. ` 2 V`D. ` 0. 5 V`

A `2 mu F` condenser is charged upto 200 volt and then battery is removed. On combining this with another uncharged condenser in parallel, the potential difference is found to be 40 volt. Find the capacity of second condenser (in `mu F`)

When thee dipole is aligned parallel to the field, its electric potential energy is …………

A molecule with a dipole moment `p` is placed in an electric field of strength `E`. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated to be anti-parallel to the field, the work required to be done by an external agency isA. `-2 pE`B. `-pE`C. `pE`D. `2pE`

A parallel plate capacitor has a capacity c. If a medium of dielectric constant K is introduced between plates, the capacity of capacitor becomesA. `C/K`B. `C/K^(2)`C. `M^(2)C`D. KC

The energy required to charge a parallel plate condenser of plate separtion `d` and plate area of cross-section `A` such that the unifom field between the plates is `E` isA. `(1)/(2)(epsilon_(0)E^(2))/(Ad)`B. `(epsilon_(0)E^(2))/(Ad)`C. `epsilon_(0)E^(2)Ad`D. `(1)/(2)(epsilon_(0)E^(2))/(Ad)`

The energy required to charge a parallel plate condenser of plate separtion `d` and plate area of cross-section `A` such that the unifom field between the plates is `E` isA. `(1)/(2)epsilon_(0)E^(2)//Ad`B. `epsilon_(0)E^(2)//Ad`C. `epsilon_(0)E^(2)Ad`D. `(1)/(2)epsilon_(0)E^(2)Ad`

When an electric dipole P `vecv` is placed in a uniform electric field `vecE` then at what angle between `vecP` and `vecE` the value of torque will be maximaA. `90^(@)`B. `0^(@)`C. `180^(@)`D. `45^(@)`

An electric dipole of moment `vecp` is placed normal to the lines of force of electric intensity `vecE`, then the work done in deflecting it through an angle of `180^(@)` isA. `Pe`B. `+2pE`C. `-2pE`D. Zero

A parallel plate capacitor with air inbetween the paltes has a capacitance of 8 pF. The separation between the plates is now reduced by half and the space between them is filled with a medium of dielectric constant 5. Calculate the new value of capacitance.

Two infinitely large plane thin parallel sheets having surface charge densities σ1 and σ2 (σ1 &gt;σ2) are shown in the figure. Write the magnitudes and directions of the net fields in the regions marked II and III.

Electric intensity at a point just outside a charged conductor of any shape isA. `sigma/(in_(0)K)`B. `sigma/(2in_(0)K)`C. `(2sigma)/(inK)`D. `(sigma^(2))/(2inK)`

The number of electrons to be put on a spherical conductor of radius `0.1m` to produce an electric field of `0.036N//C` just above its surface isA. `2.4xx10^(5)`B. `2.5xx10^(5)`C. `2.6xx10^(5)`D. `2.7xx10^(5)`

The capacitance of an isolated spherical conductor of radius R in vacuum is (A) not defined (B) zero (C) 4πε0R (D) infinite.

Capacitance (in F) of a spherical conductor with radius 1m isA. (a) `1.1xx10^-10`B. (b) `10^-6`C. (c) `9xx10^-9`D. (d) `10^-3`

The capacitance of the earth, viewed as a spherical conductor of radius 6408 km isA. `980muF`B. `1424muF`C. `712muF`D. `600muF`

Two infinitely large plane thin parallel sheets having surface charge densities σ1 and σ2 (σ1 >σ2) are shown in the figure. Write the magnitudes and directions of the net fields in the regions marked II and III.