Question

The negative terminal of 12 V battery is connected to the ground. Then the positive terminal will be at

• A. +6 V
• B. +12 V
• C. -6 V
• D. -12 V

Answer 1

Answer: (B)

+12 V

Answer 2

A 12 V battery means that the potential difference between its positive and negative terminals is 12 Volts. Let $V_+$ be the potential of the positive terminal and $V_-$ be the potential of the negative terminal.

The definition of battery voltage states: $V_+ - V_- = 12 \, \text{V}$

When a terminal is connected to the ground, its potential is set to 0 V. In this case, the negative terminal is connected to the ground. Therefore, $V_- = 0 \, \text{V}$

Substitute this value into the battery voltage equation: $V_+ - 0 \, \text{V} = 12 \, \text{V}$ $V_+ = 12 \, \text{V}$

Thus, the positive terminal will be at +12 V.