●●●WHAEATSTONE BRIDGE●●●
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| When R1=R2 & R3=R4 SO R1/R2 = R3 /R4 SO THE CENTRAL BULB (RESISTOR) DONT WORK B/C IT DOES NOT HAVE ELECTRICITY... |
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| W TWO BULBS ARE CHANGED THE R1≠R2 & R3 ≠R4 AND SO RATIO OF R1/R2≠R3/R4 SO THE CENTRAL BULB GLOWS |
A Wheatstone bridge consists of four resistors, forming a diamond-shaped circuit. Let's label the resistors as R1, R2, R3, and R4. R1 and R2 are connected in series, forming one side of the diamond, and R3 and R4 are connected in series, forming the other side. The junction between R1 and R2 is labeled A, the junction between R2 and R3 is labeled B, the junction between R3 and R4 is labeled C, and the junction between R4 and R1 is labeled D.
A galvanometer, which is an instrument used to detect and measure electric currents, is connected between junctions A and C. A power supply, such as a battery, is connected across junctions B and D to complete the circuit.
Now, let's understand the working principle of the Wheatstone bridge. When the Wheatstone bridge is balanced, it means that the resistance ratio of R1 to R2 is equal to the resistance ratio of R3 to R4. In other words, the ratio R1/R2 is the same as the ratio R3/R4. When this balance is achieved, no current flows through the galvanometer.
In an ideal Wheatstone bridge, the galvanometer will read zero when the bridge is balanced. However, in real-world situations, there may be slight imbalances due to factors like internal resistances and temperature variations.
To balance the Wheatstone bridge and achieve a reading of zero on the galvanometer, the value of one of the resistors is adjusted. This resistor is often referred to as the "unknown" resistor because its value needs to be determined. By adjusting this resistor, the bridge is brought into a balanced state, and the value of the unknown resistor can be calculated based on the known values of the other resistors.
The bridge equation provides a mathematical description of the Wheatstone bridge:
R1 / R2 = R3 / R4
Using this equation, you can calculate the unknown resistance by rearranging the equation:
R1 = (R2 * R3) / R4
The Wheatstone bridge is widely used to measure resistance accurately in various applications, including in scientific research, engineering, and electrical testing. It is a versatile circuit that allows for precise resistance measurements and has significant practical importance in many fields.
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