The minimum number of identical bulbs of rating $4\text{ V}; 6\text{ W}$ , that can work safely with desired brightness, when connected in series with a $240\text{ V}$ mains supply is :

Electricity

Options

(a)20

(b)40

(d)80

Official Answer

The minimum number of identical bulbs of rating 4 V; 6 W that can work safely with desired brightness when connected in series with a 240 V mains supply can be calculated by dividing the total voltage by the voltage of each bulb. Therefore, the minimum number of bulbs is 240 V / 4 V = 60.

series circuitsvoltagebulbs

Marking Scheme

11 mark for correct answer

Hint

Use the formula V = nV1 to calculate the minimum number of bulbs, where V is the total voltage, n is the number of bulbs, and V1 is the voltage of each bulb.

Quick Oral Answer

The minimum number of bulbs is 60.

Analysis & Explanation

This problem requires the application of the concept of series circuits. The correct answer is 60.

Common Mistakes

1Incorrect calculation of minimum number of bulbs

Interesting Facts

The concept of series circuits is important in electrical engineering and electronics.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2025?

This question carries 1 mark in the CBSE Class 10 Science 2025 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Electricity" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Electricity" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2025 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2025 paper.