Kirchoff's First Law

KIRCHOFF'S 1^ST LAW

By Mr Math n Physics

Kirchoff's First Law

​Kirchhoff’s first law is an expression of the conservation of charge. The idea is that the total amount of charge entering a point must exit the point.

In a series circuit,the currentis the same at any point

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Current in a series circuit

In a parallel circuit, the current divides at the junctions and each branch has a different value. Kirchhoff’s first law applies at each junction

​Current in a parallel circuit

Multiple Choice

A circuit consisting of five identical resistors is shown. Which of the following statements is false?

• The potential difference between P and Q is equal to the potential difference between X and Y

• The total resistance between X and Y is equal to the sum of the resistances between X and Y

• The total resistance between P and Q is equal to the sum of the resistances along P and Q

• There is less total resistance between P and Q than there is between X and Y

Multiple Choice

A circuit consisting of five identical resistors is shown. Which of the following statements is false?

• current entering A = current entering B + current entering C

• current entering D = current entering E

• current entering P = current entering X

• current entering P = current leaving Q

Multiple Choice

A cell of e .m .f. 2.0 V and negligible internal resistance is connected to a network of resistors as shown. What is the equivalent resistor on the circuit?

• 4.0 Ω

• 3.0 Ω

• 1.5 Ω

• 1.3 Ω

Multiple Choice

A cell of e .m .f. 2.0 V and negligible internal resistance is connected to a network of resistors as shown. What is the current I ?

• 1.0 A

• 1.5 A

• 2.0 A

• 2.5 A

Multiple Choice

A cell of e .m .f. 2.0 V and negligible internal resistance is connected to a network of resistors as shown. What is the current I₁ ?

• 0.50 A

• 0.75 A

• 1.0 A

• 1.25 A

Multiple Choice

A cell of e .m .f. 2.0 V and negligible internal resistance is connected to a network of resistors as shown. What is the current I₂ ?

• 0.25 A

• 0.50 A

• 0.75 A

• 1.0 A

Multiple Choice

A cell of e .m .f. 2.0 V and negligible internal resistance is connected to a network of resistors as shown. What is the current I₃ ?

• 0.25 A

• 0.50 A

• 0.75 A

• 1.0 A

Multiple Choice

The diagram shows part of a current-carrying circuit. The ammeter has negligible resistance. What is the reading on the ammeter ?

• 0.7 A

• 1.3 A

• 1.5 A

• 1.7 A