A student built an electric circuit that consists of an ideal battery, a voltmeter with resistance R_{V}, an ammeter with resistance R_{A} and a resistor R. She connected all elements in the circuit as shown in Fig. (1). The voltmeter showed a reading of 1V and the ammeter showed a current of 1A. Then, another student switched between the voltmeter and ammeter Fig. (2). As a result, the voltmeter showed the reading of 2V and the ammeter showed the current of 0.5A. What is the resistance of the resistor?

# Electric Circuits DC

# STAR connection

Three batteries have their negative terminals connected together.

Find the voltage read by an ideal voltmeter.

# When the fuse blows

A fuse is a device to avoid the flow of a large current in a circuit. The potential difference across the fuse is negligible. In our circuit, the maximum current allowed through the fuse is 10 A. The light bulbs marked 40 Watt, 110 V. The bulbs connected to a voltage source of 110 V. What is the maximum number of bulbs that can be placed in parallel before the fuse blows?

# The light bulbs are connected in series or parallel

Two identical light bulbs are connected to identical batteries in two different ways. First they are connected in series and then in parallel. In which circuit will the bulbs shine brightly? What is the ratio of the power supplied in series to the power supplied in parallel?

# The resistance of each resistor

The total resistance of the circuit is 10 Ω. If the resistors R_{1} and R_{3} are swapped then the total resistance of the circuit will increase 100 times. If the resistors R_{2} and R_{3} are swapped then the total resistance of the circuit will increase by 0.2%.

Find the resistance of each resistor.

# The Ring

A homogeneous wire is used to make a ring with a jumper on the diameter AB. What is the percentage change in the resistance between points A and B, if the jumper is cut?

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# Which of the bulbs will fuse?

Two electric bulbs marked 25W – 220V and 100W – 220V are connected in series to a 440V supply. Which of the bulbs will fuse?