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dimaraw [331]
3 years ago
8

Which is true about the resistivities of a metal and a semiconductor as the temperature is increased?

Physics
2 answers:
allochka39001 [22]3 years ago
7 0

Answer:

The resistivity of metals decreases on increase in temperature whereas the resistivity of semiconductors increases with increase in temperature.

Explanation:

The majority charge carriers in metals are electrons which are explained by the electron-sea model. The electron sea model considers metal to have a sea of conducting electrons in between the nucleus arrangement.

The nucleus is bind firmly within the lattice structure and when the temperature has increased this accounts for the lattice vibrations as a result offering obstructions to the valence electrons which increases its bulk resistivity.

The variation in the resistivity of metal is given by:

\rho=\rho_0[1+\alpha_t(T-T_0)]

where:

\alpha_t=temperature coefficient of resistivity which is defined as the fractional change in resistivity per unit change in temperature.

\rm \rho\ and\ \rho_0\ are\ the\ resistivity\ at\ temperature\ T\ and\ T_0\ respectively

At temperatures 500 K above the room temperature we have the variation of resistivity of the metal in a linear manner.

  • For semiconductors, the value of coefficient of resistivity is negative which implies that the resistivity of semiconductors decreases as temperature increases.
MAVERICK [17]3 years ago
4 0

Answer:

Explanation:

According to the electrical conductivity, there are three types of materials:

Metals are the conductors which allows the electric current to flow through them. For example, iron , copper, silver, etc.

As the temperature of a metal increases the resistivity also increases.

Semiconductors are the material which are insulators at room temperature but they behaves like a conductor as the temperature increases.

The resistivity of a semiconductor decreases as the temperature increases.

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A plane passes over Point A with a velocity of 8000 m/s north. Forty seconds later it passes over Point B at a velocity of 10,00
Airida [17]

Answer:

The planes’ acceleration from A to B is 500m/s^2

Explanation:

Given that the initial velocity u is 8000m/s

and also given the final velocity v=10,000 m/s

the time taken to move from A to B = 40 second

The acceleration is defined as the rate of change of velocity with time

we know that the expression for acceleration is given as

a=(v-u)/t

substituting our given data into the expression for a we have

a=(10000-8000)/40

a=2000/40

a=500m/s^2

The planes’ acceleration from A to B is 500m/s^2

7 0
3 years ago
Which colors allowed the most electricity to be generated
Naddik [55]
Yellow and red hope that helped
3 0
3 years ago
The electrons in the beam of a television tube have a kinetic energy of 2.20 10-15 j. initially, the electrons move horizontally
dalvyx [7]
(a) The electrons move horizontally from west to east, while the magnetic field is directed downward, toward the surface. We can determine the direction of the force on the electron by using the right-hand rule:
- index finger: velocity --> due east
- middle finger: magnetic field --> downward
- thumb: force --> due north
However, we have to take into account that the electron has negative charge, therefore we have to take the opposite direction: so, the magnetic force is directed southwards, and the electrons are deflected due south.

b) From the kinetic energy of the electrons, we can find their velocity by using
K= \frac{1}{2}mv^2
where K is the kinetic energy, m the electron mass and v their velocity. Re-arranging the formula, we find
v= \sqrt{ \frac{2K}{m} }= \sqrt{ \frac{2 \cdot 2.20 \cdot 10^{-15} J}{9.1 \cdot 10^{-31} kg} }=6.95 \cdot 10^7 m/s

The Lorentz force due to the magnetic field provides the centripetal force that deflects the electrons:
qvB = m \frac{v^2}{r}
where
q is the electron charge
v is the speed
B is the magnetic field strength
m is the electron mass
r is the radius of the trajectory
By re-arranging the equation, we find the radius r:
r= \frac{mv}{qB}= \frac{(9.1 \cdot 10^{-31} kg)(6.95 \cdot 10^7 m/s)}{(1.6 \cdot 10^{-19} C)(3.00 \cdot 10^{-5} T)}=13.18 m

And finally we can calculate the centripetal acceleration, given by:
a_c =  \frac{v^2}{r}= \frac{(6.95 \cdot 10^7 m/s)^2}{13.18 m}=3.66 \cdot 10^{14} m/s^2
5 0
3 years ago
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Answer:

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Explanation:

6 0
3 years ago
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A child in a tree house uses a rope attached to a basket to lift a 24 N dog upward through a distance of 4.9 m into the house.
jenyasd209 [6]
<h3>Answer:</h3>

117.6 Joules

<h3>Explanation:</h3>

<u>We are given;</u>

  • Force of the dog is 24 N
  • Distance upward is 4.9 m

We are required to calculate the work done

  • Work done is the product of force and distance
  • That is; Work done = Force × distance
  • It is measured in Joules.

In this case;

Force applied is equivalent to the weight of the dog.

Work done = 24 N × 4.9 m

                  = 117.6 Joules

Hence, the work done in lifting the dog is 117.6 Joules

3 0
3 years ago
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