Class 10 Exam  >  Class 10 Questions  >  Two lamps , rated 60 W at 220V and other 40 W... Start Learning for Free
Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ?
Most Upvoted Answer
Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected...
**Analysis:**

When two lamps are connected in series, they share the same current. The potential difference across each lamp depends on their respective resistances. The brightness of a lamp is directly proportional to the power it consumes. Therefore, the lamp with higher power consumption will glow more brightly.

**Calculations:**

To determine the brightness of each lamp, we need to calculate the current passing through them and the potential difference across each lamp.

Given:
- Lamp 1: Power (P1) = 60 W, Voltage (V1) = 220 V
- Lamp 2: Power (P2) = 40 W, Voltage (V2) = 220 V

**Step 1: Calculate the resistance of each lamp:**

The resistance of a lamp can be calculated using Ohm's law: R = V^2 / P, where R is resistance, V is voltage, and P is power.

- Resistance of Lamp 1 (R1) = (220^2) / 60 = 806.67 Ω
- Resistance of Lamp 2 (R2) = (220^2) / 40 = 1210 Ω

**Step 2: Calculate the total resistance of the circuit:**

In a series circuit, the total resistance is the sum of individual resistances.

- Total Resistance (RTotal) = R1 + R2 = 2016.67 Ω

**Step 3: Calculate the current passing through the circuit:**

The current passing through the circuit can be calculated using Ohm's law: I = V / R, where I is current, V is voltage, and R is resistance.

- Total Current (ITotal) = 220 / 2016.67 = 0.109 A

**Step 4: Calculate the potential difference across each lamp:**

The potential difference across each lamp can be calculated using Ohm's law: V = IR, where V is voltage, I is current, and R is resistance.

- Voltage across Lamp 1 (V1) = 0.109 * 806.67 = 88.00 V
- Voltage across Lamp 2 (V2) = 0.109 * 1210 = 132.19 V

**Conclusion:**

Based on the calculations, the lamp with a power rating of 40 W will glow more brightly. This is because it has a higher voltage across it compared to the lamp with a power rating of 60 W. The voltage across a lamp determines its brightness, and in this case, Lamp 2 has a higher voltage, resulting in a brighter glow.
Community Answer
Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected...
We have given two lamps in such a way :
Power of 1st lamp, P₁ = 40W , voltage of 1st lamp, V₁ = 220V
power of 2nd lamp , P₂ = 60W , voltage of 2nd lamp ,V₂ = 220V

we know, one things ,
Power = V²/R [ when potential difference is same then consider P = V²/R ]
R = V²/P
so, resistance of 1st lamp , R₁ = V₁²/P₁ = (220)²/60 = 4840/6 = 2420/3Ω
resistance of 2nd lamp , R₂ = V₂²/P₂ = (220)²/40 = 48400/40 = 1210Ω
Now, question said ,
(a) Both the lamps are in parallel ,
So, 1/Req = 1/R₁ + 1/R₂
1/Req = 3/2420 + 1/1210 = 5/2420 = 1/484
Req = 484Ω

Now, Current drawn from electrical supply ,i = potential difference/Req
= 220V/484 = 20/44 = 5/11 A

(b) energy consumed by lamps in one hour = Energy consumed by 1st lamps in one hour + energy consumed by 2nd lamps in one hour
= P₁ × 1hour + P₂ × 1 hour
=(P₁ + P₂) × 1 hour
= (60W + 40W) × 1 hour
= 100 Wh
= 100/1000 KWh [ ∵ 1 KWh = 10²Wh ]
= 0.1 KWh
Attention Class 10 Students!
To make sure you are not studying endlessly, EduRev has designed Class 10 study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Class 10.
Explore Courses for Class 10 exam

Top Courses for Class 10

Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ?
Question Description
Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? for Class 10 2024 is part of Class 10 preparation. The Question and answers have been prepared according to the Class 10 exam syllabus. Information about Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? covers all topics & solutions for Class 10 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ?.
Solutions for Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? in English & in Hindi are available as part of our courses for Class 10. Download more important topics, notes, lectures and mock test series for Class 10 Exam by signing up for free.
Here you can find the meaning of Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? defined & explained in the simplest way possible. Besides giving the explanation of Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ?, a detailed solution for Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? has been provided alongside types of Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? theory, EduRev gives you an ample number of questions to practice Two lamps , rated 60 W at 220V and other 40 W at 220 V , are connected in series to an electric supply at 220 V. Which bulb will glow more bright ? tests, examples and also practice Class 10 tests.
Explore Courses for Class 10 exam

Top Courses for Class 10

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev