Electric Dipole

Rarely Tested

Electric Dipole

An electric dipole consists of two equal and opposite charges separated by a small distance.

### Dipole Moment

$$p=q(2a)$$

### Terminologies

- p → Electric dipole moment.

- q → Magnitude of charge.

- 2a → Separation between charges.

### SI Unit

$$Cm$$

### Dimensions

$$[p]=[LTA]$$

### Conditions / Special Cases

- Direction of dipole moment is from negative charge to positive charge.

### Usage

- Used in electric field and torque problems.

Question 1

Consider an electric dipole comprising two charges $$+q$$ and $$-q$$ each with mass $$m$$, separated by a fixed distance $$d$$ and initially at rest with its dipole moment pointing along $$\hat{i}$$. A uniform electric field $$E\hat{j}$$ is turned on at time $$t=0$$ and it is turned off at $$t=t_f$$, when the dipole moment makes an angle $$\theta_f$$ with $$\hat{i}$$. Neglecting any sources of energy loss, correct option(s) is/are:

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