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Bridge circuit

physical science Maturity 11-13 Next article →

A bridge circuit is a special way to set up electric paths. It uses two main branches of a circuit. A third branch connects these two paths at a middle point. This third path is called a bridge.

Mesh Analysis-bridge circuit
Mesh Analysis-bridge circuit

This setup is very useful for measuring things. Scientists use it in tools and for power conversion. It can also help with filtering signals. It is a clever way to look at electricity.

To see how it works, think about comparing two paths. The circuit compares two potential dividers that share one source.

Mesh Analysis-bridge circuit
Mesh Analysis-bridge circuit

One famous version is the Wheatstone bridge. This uses four resistors, which are parts that resist electric flow. Two resistors have known values. One resistor is a variable one that you can change. The last resistor is the unknown one you want to measure.

Mesh Analysis-bridge circuit
Mesh Analysis-bridge circuit

You connect a battery to the circuit to provide current. A tool called a galvanometer is also connected across the paths.

History shows us how these ideas grew over time. Samuel Hunter Christie first invented the Wheatstone bridge. Later, Charles Wheatstone made the design very popular.

Mesh Analysis-bridge circuit
Mesh Analysis-bridge circuit

People have since made many different versions. There is the Wien bridge and the Maxwell bridge. There is also the Heaviside bridge. This specific one measures mutual inductance. These discoveries helped us understand electricity much better. They allow us to measure many different things.

There are many specific facts about how these tools work. In a Wheatstone bridge, you adjust the variable resistor. You do this until the galvanometer reads exactly zero.

Mesh Analysis-bridge circuit
Mesh Analysis-bridge circuit

When it hits zero, you can use a ratio to find the answer. The ratio of the variable resistor to its neighbor is the same as the unknown one. This allows you to calculate the unknown value. You can also measure inductance and capacitance this way. Some bridges even work with AC circuits to measure impedance.

Bridge circuits are part of many things you see today. A bridge rectifier uses diodes to change electric current. This process is called rectification. It turns an unknown current into a direct current. This makes the flow steady and known.

Mesh Analysis-bridge circuit
Mesh Analysis-bridge circuit

You might also find an H-bridge in motor controllers. This helps a motor turn in different directions. These circuits are all about balance and control. They make our modern technology work smoothly.

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