Tần số ngưỡng của một kim loại có giá trị X. Nếu tần số của chùm sáng chiếu đến bề mặt katot tăng từ 2X đến 4X thì cường độ dòng
1 answer:
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The electrostatic force between the two ions is
Explanation:
The electrostatic force between two charged particle is given by Coulomb's law:
where
is the Coulomb's constant
are the two charges
r is the separation between the two charges
In this problem, the ion of sodium has a charge of
while the ion of chlorine has a charge of
And the distance between the two ions is
Substituting, we find the electrostatic force between the two ions:
where the negative sign simply means that the force is attractive, since the two ions have opposite charge.
Learn more about electrostatic force:
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The unknown substance can be lithium, which has a specific heat capacity of approximately .
Explanation:
When heat energy is supplied to a certain substance, the temperature of the substance increases according to the equation:
where
Q is the amount of energy supplied
m is the mass of the sample
is the specific heat capacity of the substance
is the change in temperature
In this problem, we have
m = 4.9 g is the mass
Q = 668.85 J is the specific heat capacity
is the change in temperature
Solving for , we find the specific heat capacity of the substance:
Looking at tables of specific heat capacity, we can see that the unknown substance can be lithium, which has a specific heat capacity of approximately .
Learn more about specific heat capacity:
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