In the two circuits at right, both batteries are ideal and identical. The two am
ID: 2147746 • Letter: I
Question
In the two circuits at right, both batteries are ideal and identical. The two ammeters are also ideal and identical. The current through ammeter At is equal to that through ammeter A2. Resistor R1 has a value of 10 Ohm. Is the resistance of bulb A greater than, less than, or equal to 10 ft? The resistance of bulb A is greater than 10 Ohm. The resistance of bulb A is less than 10 Ohm. The resistance of bulb A is equal to 10 Ohm. There is not enough information to answer the question. Explain your reasoning. A second identical bulb, B, is added in series to bulb A as shown at right. When bulb B is added in series with bulb A, does the current reading on ammeter A2 increase, decrease, or remain the same? The current reading on ammeter A2 increases. The current reading on ammeter A2 decreases. The current reading on ammeter A2 remains the same. There is not enough information to answer the question.Explanation / Answer
Since current = voltage / resistance, Resistance = voltage/current. It is given that the batteries are identical (same voltage and internal resistance) and the ammeter readings are same (so current is same). So, the resistances are equal. If a second identical bulb is added in series to bulb, the total resistance will be doubled. So, the current will be halved. So, reading on A2 decreases.