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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Answer:
Explanation:
Electron's kinetic energy = 2 eV
= 2 x 1.6 x 10⁻¹⁹ J
1/2 m v² = 3.2 x 10⁻¹⁹
1/2 x 9.1 x 10⁻³¹ x v² = 3.2 x 10⁻¹⁹
v² = .703 x 10¹²
v = .8385 x 10⁶ m/s
Electrons revolve in a circular orbit when forced to travel in a magnetic field whose radius can be expressed as follows
r = mv / Bq
where m , v and q are mass , velocity and charge of electron .
here given magnetic field B = 90 mT
= 90 x 10⁻³ T
Putting these values in the expression above
r = mv / Bq
=
= .052 mm.