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# Hot water is poured simultaneously in four metallic tumblers painted outside with different paints. After some time the water will be found to have cooled most in the tumbler painted.

 A) rough white B) rough black C) shining white D) shining black

Explanation:

Black surfaces are good emitters of heat. If the black surface is rough too, the emitting will be better. Shinning surfaces reflect black radiation . So if the black surface is also shining the effectiveness of emitting heat is lessened.

Subject: Physics

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• Related Questions

On the Kelvin scale ,the melting point of ice is

 A) 373K B) 100K C) 273K D) 0 K

Explanation:

Subject: Physics

1

Water has maximum density at............

 A) 0 C B) -15 C C) 4 C D) 15 C

Explanation:

Subject: Physics

0

Fish and other aquatic creatures canlive inside a deep frozen pond because

 A) fish are cold-blooded animals B) ice is a bad conductor of heat C) there will always be water just beneath the ice level D) they can adapt themselves to live in ice

Answer & Explanation Answer: C) there will always be water just beneath the ice level

Explanation:

Water has maximum density at $\inline \fn_jvn 4^{0}C$. So at this temperature it sinks down to bottom and stays here. If it cools further, it will become less dense and move up. So while the upper layers can cool enough to form ice, the bottom layers remain as water at $\inline \fn_jvn 4^{0}C$$\inline \fn_jvn \therefore$ (C) is correct.

Subject: Physics

11

At what temperature do the Fahrenheit and celcius scales give the same reading?

 A) 212 degrees B) 32 degreees C) -40 degreees D) 0 degreees

Explanation:

$\inline \fn_jvn F=C\times \frac{9}{5}+32$ We want the temperaature when F=C. So substituting C For F, we have C = $\inline \fn_jvn F=C\times \frac{9}{5}+32$

$\inline \fn_jvn \therefore$ C = -40. Thus when C = -40, we have C = F i.e, $\inline \fn_jvn -40^{0}F$

$\inline \fn_jvn \therefore$ (C) is coorrect. i.e,$\inline \fn_jvn -40^{0}C=-40^{0}F$

Subject: Physics

12

Pieces of camphor placed on water move about rapidly. This is because of

 A) diffusion B) viscosity C) surface tension D) capillarity