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Novay_Z [31]
3 years ago
12

How does a vacuum flask keep drinks hot? Explain in terms of conduction, convection and radiation.

Physics
1 answer:
Flura [38]3 years ago
4 0
Vacum flask has inner layer of glass and outer body of plastic.the glass has a reflective metal layer..when a hot drink is poured into the flask it prevents conduction.tight lid stops the convection.when radiation tries to leave the hot drink the reflective layer of the glass reflects it back so no heat can escape.
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Select the correct statement about osmolarity. a) Osmolarity measures the moles of solute per liter of solution. b) The contents
8090 [49]

Answer:

a) Osmolarity measures the moles of solute per liter of solution.

Explanation:

Osmolarity is defined as the number of moles of solute that contribute to the osmotic pressure, per liter of solution, of solution. That is, the measurement of the solute concentration. The prefix "osmo-" indicates the possible variation of the osmotic pressure in the cells, which will occur when the solution is introduced into the body.

7 0
3 years ago
The work function for tungsten metal is 4.52eV a. What is the cutoff (threshold) wavelength for tungsten? b. What is the maximum
Tanya [424]

Answer: a) 274.34 nm; b) 1.74 eV c) 1.74 V

Explanation: In order to solve this problem we have to consider the energy balance for the photoelectric effect on tungsten:

h*ν = Ek+W ; where h is the Planck constant, ek the kinetic energy of electrons and W the work funcion of the metal catode.

In order to calculate the cutoff wavelength we have to consider that Ek=0

in this case  h*ν=W

(h*c)/λ=4.52 eV

λ= (h*c)/4.52 eV

λ= (1240 eV*nm)/(4.52 eV)=274.34 nm

From this h*ν = Ek+W;  we can calculate the kinetic energy for a radiation wavelength of 198 nm

then we have

(h*c)/(λ)-W= Ek

Ek=(1240 eV*nm)/(198 nm)-4.52 eV=1.74 eV

Finally, if we want to stop these electrons we have to applied a stop potental equal to 1.74 V . At this potential the photo-current drop to zero. This potential is lower to the catode, so this  acts to slow down the ejected electrons from the catode.

5 0
3 years ago
Which planet has the GREATEST attraction to the sun?
AveGali [126]
I think its Mercury because it's the closest to the sun.
3 0
3 years ago
Will a substance that contains an o-h group dissolve in water?
Stella [2.4K]
Usually, it increases the solubility in water.
4 0
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How many atoms are in a sample of 2.39 moles of neon (Ne) atoms?
Reil [10]
<span>Avogadro's number represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles.

 </span>2.39 moles Ne ( 6.022 x 10^23 atoms / mole ) = 1.44 × 10^24 atoms Ne
4 0
3 years ago
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