Metre Bridge (Resistance of a wire) Video Lecture | Physics Class 12 - NEET

Ans. A metre bridge is a device used to measure the resistance of a wire. It consists of a uniform wire of known resistance, a galvanometer, a jockey, and a battery. The wire is connected in series with the unknown resistance, and a jockey is used to slide along the wire. By finding the balance point where the galvanometer shows zero deflection, the ratio of the two resistances can be determined, allowing the calculation of the unknown resistance.

Ans. To calculate the unknown resistance using a metre bridge, follow these steps: 1. Connect the unknown resistance in series with the wire of known resistance on the metre bridge. 2. Slide the jockey along the wire until the galvanometer shows zero deflection. 3. Measure the distances on either side of the jockey, denoting them as L1 and L2. 4. Calculate the ratio of the unknown resistance to the known resistance as R = L1/L2. 5. Use the formula R = (100 - R)/R, where R represents the calculated ratio, to find the value of the unknown resistance.

Ans. Yes, a metre bridge can be used to measure the resistance of any wire as long as the wire can be connected in series with the known resistance. However, the wire should have a low resistance compared to the known resistance to ensure accurate measurements. Additionally, the wire should have a uniform cross-section and be made of a material with a linear resistance-temperature relationship.

Ans. Some limitations of using a metre bridge for resistance measurement include: 1. The accuracy of the measurement depends on the sensitivity of the galvanometer used. 2. The resistance of the wire used in the metre bridge should be low compared to the unknown resistance to avoid significant errors. 3. The wire should have a linear resistance-temperature relationship, as temperature variations can affect the accuracy of the measurement. 4. The metre bridge assumes that the connecting wires have negligible resistance, which may not always be the case. 5. The accuracy of the measurement can be affected by external factors like temperature variations and the presence of magnetic fields.

Ans. No, a metre bridge is not suitable for measuring the resistance of a wire with high resistance. The metre bridge works on the principle of finding a balance point, and this becomes difficult when the unknown resistance is significantly larger than the known resistance. In such cases, other methods like Wheatstone bridge or potentiometer are more suitable for accurate resistance measurements.