What is main cause of sleep paralysis?

Student X answered  •  5 hours ago
Lack of sleep is one of the major cause,but it can be also caused by stress and some medications

Schematic diagram of an electrolytic cell is
  • a)
  • b)
  • c)
  • d)
    None of these is the correct presentation
Correct answer is option 'B'. Can you explain this answer?

Mahesh Mahajan answered  •  6 hours ago
Yes B is correct option because anions are negatively charged and they will get attracted towards electrode having positive charge i.e anode and similar for cathode

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If the resistance of a conductor is 5 Ω at 50ºCand 7Ω at 100ºC, then the mean temperature coefficient of resistance (of the material) is[1996]
  • a)
    0.013/ºC
  • b)
    0.004/ºC
  • c)
    0.006/ºC
  • d)
    0.008/ºC
Correct answer is option 'A'. Can you explain this answer?

Chameli Devi answered  •  7 hours ago
We know that R(T)=R(0)(1+αT)  
where R(T)= resistance at temp T, 
R0= resistance at temp T=0oC 
and α= temperature coefficient of resistance.
Here, 5=R0(1+α.50)...(1)
and 7=R0(1+α.100)...(2)
(2)/(1)
⇒7/5=(1+100α)/(1+50α) 
7+350α=5+500α
150α=2
⇒α=2/150
=0.013/ºC

Who indirectly determined the mass of theelectron by measuring the charge of the electron?     [2000]
  • a)
    Thomson
  • b)
    Rutherford
  • c)
    Einstein
  • d)
    Millikan
Correct answer is option 'D'. Can you explain this answer?

Bimla answered  •  7 hours ago
Correct Answer :- D
Explanation : The mass of the electron is discovered by  the Millikan by the oil drop experiment.
E = mg
=> qE = mg
q/m = g/E
Therefore, charge was quantised.

Each plate of a parallel plate capacitor has a charge q on it. The capacitor is now connected to a battery. Now,
  • a)
     The facing surfaces of the capacitor have equal and opposite charges
  • b)
    The two plates of the capacitor have equal and opposite charges
  • c)
     The battery supplies equal and opposite charges to the two plates
  • d)
    The outer surfaces of the plates have equal charges
Correct answer is option 'A,B,D'. Can you explain this answer?

Om Vati answered  •  7 hours ago
(a) The facing surfaces of the capacitor have equal and opposite charges
(b) The two plates of the capacitor have equal and opposite charges
(d) The outer surfaces of the plates have equal charges
Explanation:
q-Q=q+QàQ=0
  • Please note, option (c) is incorrect the reason being why is that the battery is a source of energy not charge.
  • If a capacitor plates have equal charge on outside and equal charge on inside, then one can think that the charge on the plates must be equal so option (b) cannot be incorrect.

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