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- Question
Brightness of bulb depends on voltage or current?
Options- A. Current
- B. Voltage
- C. Both A & B
- D. None
- Correct Answer
- Both A & B
ExplanationBrightness of bulb depends on both voltage and current. The brightness depends on power.
Since we know that Power (P) = Voltage x Current = V I
So whether you increase the current or the voltage the brightness will increase.
Example Illustration:
If you connect a long bulb and a round bulb in series, the long bulb glows but the round bulb does not. Both of them have the same current flowing through them (they are in series) but the long bulb has a greater voltage across it because it has more resistance (even though V= IR is not obeyed exactly, voltage drop does depend on the resistance). If you connect a round bulb and a long bulb in parallel, however, it is the round bulb that is brighter because now the voltage across both bulbs is the same but the current is larger through the round bulb (smaller resistance).
Hence, the brightness of a bulb depends on power i.e, both voltage and current.
- 1. Reading of a barometer going down is an indication of
Options- A. Storm
- B. Rainfall
- C. Snow
- D. Intense heat Discuss
- 2. Fog is an example of a
Options- A. liquid dispersed in gas
- B. solid dispersed in liquid
- C. liquid dispersed in solid
- D. gas dispersed in liquid Discuss
- 3. The Capacity of a Communication Channel is Measured in
Options- A. Band rate
- B. Band width
- C. Data flow
- D. Bit capacity Discuss
- 4. A convex mirror is used to form an image of a real object. The image
Options- A. is diminished in size
- B. is erect
- C. always lies between the pole and the focus
- D. all of the above Discuss
- 5. Two metallic plate of equal thickness and coefficient thermal conductivity K1 and K2 put together face to face. A common plate is constructed. What is equivalent K?
Options- A. K1k2/k1+k2
- B. 2k1k2/k1+k2
- C. K1+k2/k1k2
- D. None Discuss
- 6. As the object covers equal distances in equal intervals of time, it is said to be in ____________ motion.
Options- A. uniform
- B. linear
- C. translational
- D. equilibrium Discuss
- 7. Water kept in an earthen pot is less cool on rainy days than in summer because during the rainy days
Options- A. the pores in the pot are closed
- B. rain water stops oozing out from the pores
- C. the water that oozes out does not evaporate quickely because of the large percent age of moisture in the air
- D. surface of the pot becomes damp Discuss
- 8. Hydrogen atom is excited from ground state to another state with principal quantum number equal to 4. Then the number of spectral lines in the emission spectra will be
Options- A. 2
- B. 6
- C. 5
- D. 3 Discuss
- 9. When an electric bulb breaks , there is an explosive sound. That is due to
Options- A. the chemical reaction between the gases inside the bulb
- B. the compressed gases inside rushing out suddenly
- C. the air outside rushing in to fill the vacuum inside the bulb
- D. None of these Discuss
- 10. Energy is continuously generated in the sun due to
Options- A. Nuclear fusion
- B. Nuclear fission
- C. Radioactivity
- D. Artificial radioactivity Discuss
Physics problems
Search Results
Correct Answer: Rainfall
Explanation:
Barometer is instrument which is used to measure to pressure. A slow downfall of reading suggests a low pressure area is passing in a nearby region, it may rains. If the reading is going down very fast then its an indication of storm (within 5-6 hours).
Correct Answer: liquid dispersed in gas
Correct Answer: Band width
Explanation:
The path that data takes from source to destination is called a Channel. A channel is a communication medium. A channel has a certain capacity for transmitting information.
The "capacity" of a channel is the theoretical upper-limit to the bit rate over a given channel that will result in negligible errors. Channel capacity is often measured by its Bandwidth in Hz or its data rate in bits per second.
Correct Answer: all of the above
Correct Answer: 2k1k2/k1+k2
Explanation:
We know that,
The equivalent K =
where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.
But here L1 = L2 = L (say)
Then K = L+L/(L/K1 + L/K2) =
Correct Answer: uniform
Correct Answer: the water that oozes out does not evaporate quickely because of the large percent age of moisture in the air
Explanation:
To evaporate the water that oozes out, heat is required. Part of this heat is taken from the water inside which therefore become cool. Therefore (C) is correct. Here evaporation is less, so cooling too is less.
Correct Answer: 6
Explanation:
Number of spectral lines from a state n to ground state is
n(n-1)/2 = 6
Correct Answer: the air outside rushing in to fill the vacuum inside the bulb
Explanation:
The inside of the bulb being a vacuum, the outside air rushes in when the bulb is broken. The vibrations of the rushing air molecules produce the sound.
Correct Answer: Nuclear fusion
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