Electric dipole, field due to dipole, torque in uniform field
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See all →- Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.Assertion A : The potential (V) at any axial point, at 2 m distance(r) from the centre of the dipole of dipole moment vector P of magnitude, 4×10^-6… Answer: 4. A is true but R is false. Key idea: Potential of a dipole at an axial point: V=±p/4πε₀r² . Assertion: V=frac9×10⁹×4×10⁻⁶2²=9×10³... 1
- An electric dipole is placed at an angle of 30^° with an electric field of intensity 2×10^5 N C^-1. It experiences a torque equal to 4 N m. Calculate the magnitude of charge on the dipole, if the dipole length is 2 cm. Answer: 1. 2 mC Torque on a dipole: τ = pEsinθ , with p=q· l . 4 = q(0.02)(2×10⁵)sin30^° = q× 2000 q = 2×10⁻³ C = 2 mC. 1
- Two point charges -q and +q are placed at a distance of L, as shown in the figure.The magnitude of electric field intensity at a distance R (R>>L) varies as : Answer: 3. 1/R³ The two charges form an electric dipole with dipole moment p=qL . Their fields nearly cancel at a large distance. For Rgg L... 1
- A dipole is placed in an electric field as shown. In which direction will it move ? Answer: 2. towards the right as its potential energy will decrease. Key idea: in a non-uniform field a dipole feels a net force towards the... 1
- A short electric dipole has a dipole moment of 16×10^-9 C m. The electric potential due to the dipole at a point at a distance of 0.6 m from the centre of the dipole, situated on a line making an angle of 60^° with the dipole axis is :≤ft(1/4πε_0 = 9… Answer: 2. 200 V Potential of a short dipole: V=1/4πε₀pcosθ/r² . V=frac9×10⁹×16×10⁻⁹×cos60^°(0.6)²=144×0.5/0.36=200\ V Answer: option 2. 1
- An electric dipole is placed at an angle of 30° with an electric field intensity 2×10^5 N/C. It experiences a torque equal to 4 N m. The charge on the dipole, if the dipole length is 2 cm, is Answer: 1. 2 mC Torque on a dipole: τ=pEsinθ , with p=q l . 4=q(0.02)(2×10⁵)sin30^°=q×2000 q=4/2000=2×10⁻³ C =2 mC. Option (1). 1