Two thin dielectric slabs of dielectric constants \(K_1\) and \(K_2\) \((K_1<K_2)\) are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field \('E'\) between the plates with distance \('d'\) as measured from the plate \(P\) is correctly shown by:
1. | 2. | ||
3. | 4. |
A conducting sphere of the radius \(R\) is given a charge \(Q.\) The electric potential and the electric field at the centre of the sphere respectively are:
1. | \(\frac{Q}{4 \pi \varepsilon_0 {R}^2}\) | zero and2. | \(\frac{Q}{4 \pi \varepsilon_0 R}\) and zero |
3. | \(\frac{Q}{4 \pi \varepsilon_0 R}\) and \(\frac{Q}{4 \pi \varepsilon_0{R}^2}\) | 4. | both are zero |
\(A\), \(B\) and \(C\) are three points in a uniform electric field. The electric potential is:
1. | \(B\) | maximum at
2. | \(C\) | maximum at
3. | \(A, B\) and \(C\) | same at all the three points
4. | \(A\) | maximum at
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 \(\theta\) with the direction of the field. Assuming that the potential energy of the dipole to be zero when \(\theta = 90^{\circ}\), the torque and the potential energy of the dipole will respectively be:
1. \(pE\text{sin}\theta, ~-pE\text{cos}\theta\)
2. \(pE\text{sin}\theta, ~-2pE\text{cos}\theta\)
3. \(pE\text{sin}\theta, ~2pE\text{cos}\theta\)
4. \(pE\text{cos}\theta, ~-pE\text{sin}\theta\)
Four-point charges \(-Q, -q, 2q~\text{and}~2Q\) are placed, one at each corner of the square. The relation between \(Q\) and \(q\) for which the potential at the center of the square is zero is:
1. | \(Q= -q\) | 2. | \(Q= -2q\) |
3. | \(Q= q\) | 4. | \(Q= 2q\) |
A parallel plate condenser has a uniform electric field \(E\) (V/m) in the space between the plates. If the distance between the plates is \(d\) (m) and the area of each plate is \(A\) (m2), the energy (joule) stored in the condenser is:
1. \( \frac{1}{2}\varepsilon_0{E}^2 \)
2. \( \frac{{E}^2 {Ad}}{\varepsilon_0} \)
3. \( \frac{1}{2}\varepsilon_0 E^2 Ad \)
4. \(\varepsilon_0 EAd \)
Four electric charges \(+ q,\) \(+ q,\) \(- q\) and \(- q\) are placed at the corners of a square of side \(2L\) (see figure). The electric potential at point \(A\), mid-way between the two charges \(+ q\) and \(+ q\) is:
1. \(\frac{1}{4 \pi\varepsilon_{0}} \frac{2 q}{L} \left(1 + \frac{1}{\sqrt{5}}\right)\)
2. \(\frac{1}{4 \pi\varepsilon_{0}} \frac{2 q}{L} \left(1 - \frac{1}{\sqrt{5}}\right)\)
3. zero
4. \(\frac{1}{4 \pi \varepsilon_{0}} \frac{2 q}{L} \left(1 + \sqrt{5}\right)\)
A series combination of n1 capacitors, each of value C1, is charged by a source of potential difference 4V. When another parallel combination of n2 capacitors, each of value C2, is charged by a source of potential difference V, it has the same (total) energy stored in it, as the first combination has. The value of C2, in terms of C1, is then:
1.
2.
3.
4.
1. | \(\mathrm{V}_{\mathrm{C}}=\mathrm{V}_{\mathrm{A}} \neq \mathrm{V}_{\mathrm{B}}\) |
2. | \(\mathrm{V}_{\mathrm{C}}=\mathrm{V}_B \neq \mathrm{V}_{\mathrm{A}}\) |
3. | \(\mathrm{V}_{\mathrm{C}} \neq \mathrm{V}_B \neq \mathrm{V}_A\) |
4. | \(\mathrm{V}_{\mathrm{C}}=\mathrm{V}_B=\mathrm{V}_A\) |
Three capacitors each of capacitance \(C\) and of breakdown voltage \(V\) are joined in series. The capacitance and breakdown voltage of the combination will be:
1.
2.
3.
4. \(3C,~3V\)