Question

There are two types of bulbs available in the store. One is 40 volts and one is 60 volts. A bulb of higher voltage can work on a low voltage

supply with the help of a transformer. A bulb of lower voltage will burst at higher voltage supply without a transformer. Which of the below
statements is true?

Answer 1

In relation to electric power, voltage is directly proportional to current, based on Ohm's Law, and power is the product of voltage and current. A higher wattage bulb has lower resistance and draws more current at the same voltage. Series-wired bulbs divide voltage, affecting their brightness and function if one bulb fails.

Step-by-step explanation:

Understanding Electric Power, Voltage, Current, and Resistance

The relationship between voltage, current, and resistance in regards to electric power is based on Ohm's Law and the power equation. The power delivered to a device (in this case light bulbs) is equal to the voltage multiplied by the current (P = V × I). According to Ohm's Law, the current flowing through a conductor between two points is directly proportional to the voltage across the two points (I = V / R). It implies that as the voltage increases, holding resistance constant, both current and power would also increase.

For the 25-W bulb operating normally at 120 V, if the voltage is doubled to 240 V without using a transformer, the current and consequently the power would also double, leading to the bulb burning out quickly. When comparing a 25-W bulb and a 60-W bulb operating at the same voltage, the 60-W bulb has a lower resistance because it draws more current to achieve higher power output. The resistance in a bulb determines how much current it will draw at a given voltage, affecting both its brightness and temperature.

The example of holiday lights wired in series illustrates this concept further. For a string of 40 bulbs on a 120 V supply, each bulb would normally operate at 3 V (120 V / 40 bulbs). If one bulb in an old string burns out, it opens the circuit causing all other bulbs to go out. However, in a newer string, if a bulb shorts out, the voltage is redistributed among the remaining bulbs, potentially causing an increase in voltage per bulb (for example, 120 V / 39 bulbs) and could shorten the lifespan or burn out the other bulbs due to the increased power.

In the case of two bulbs rated 60 W and 100 W connected in series, the bulb with the lower resistance (60 W) will typically be brighter because it draws more current, causing it to receive more power in a series circuit.