Nichrome Heating Element: Assertion and Reason Analysis

This question asks us to evaluate an assertion about the use of Nichrome as a heating element and a reason given for it. Let's break down both parts.

Analyzing Assertion (A): Nichrome in Heating Devices

The assertion states that Nichrome is used as a heating element in devices like electric toasters and electric geysers. This is a well-known fact in basic physics and electronics. Nichrome, an alloy typically made of about 80% nickel and 20% chromium, is chosen for these applications because it possesses specific properties suitable for generating heat when electric current passes through it.

• It can withstand high temperatures without significant oxidation or degradation.
• It offers good resistance to heat.

Therefore, Assertion (A) is true.

Analyzing Reason (R): Properties of Nichrome

The reason given is that Nichrome has a high melting point and low resistivity. Let's examine these properties:

• High Melting Point: Nichrome does have a high melting point (around 1400 °C). This is crucial for heating elements, as they operate at high temperatures and must not melt. So, the "high melting point" part is correct.
• Low Resistivity: This part of the statement is incorrect. For a material to function effectively as a heating element, it needs to resist the flow of electric current significantly, thereby converting electrical energy into heat energy efficiently. The amount of heat generated is directly proportional to the resistance of the material (as shown in Joule's law, $H = I^2Rt$, where $H$ is heat, $I$ is current, $R$ is resistance, and $t$ is time). Materials with high resistivity are better suited for heating elements because they generate more heat for a given current and length. Nichrome has a relatively high electrical resistivity, which is why it's suitable for heating elements, not low resistivity. Low resistivity materials (like copper) are used for conducting wires where minimal heat generation is desired.

Since the reason claims Nichrome has *low* resistivity, which is false, Reason (R) is false.

Conclusion

Based on the analysis:

• Assertion (A) is true.
• Reason (R) is false.

This corresponds to the option stating that (A) is true and (R) is false.