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2 years ago

Heat transfer by radiation depends on ____

Physics

1 answer:

notsponge [240]2 years ago

5 0

Answer:

Infrared

Explanation:

This is the electromagnetic spectrum just above the visible light spectrum with higher energy (and higher frequency). This electromagnetic radiation is responsible for feeling the heat when you place your hand close to the side of a fire. It is also harnessed in night vision where bodies that emit some form of heat are visible due to their emission of IR.

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A metal sphere of radius 2.0 cm carries an excess charge of 3.0 μC. What is the electric field 6.0 cm from the center of the sph

Nonamiya [84]

Answer:

The electric field is $E = 7.5 *10^{6} \ N/C$

Explanation:

From the question we are told that

The radius of the metal sphere is $R = 2.0 \ cm = 0.02 \ m$

The excess charge which the metal sphere carries is $q = 3.0 \mu C = 3.0*10^{-6} \ C$

The distance of the position being to the center is $D = 6.0 \ cm = 0.06 \ m$

The coulomb constant is $k =9*10^{9} \ N \cdot m^2 /C^2$

Generally the electric field is mathematically represented as

$E = \frac{k * q}{D^2}$

substituting values

$E = \frac{9*10^{9} * 30.*10^{-6}}{(0.06)^2}$

$E = 7.5 *10^{6} \ N/C$

5 0

2 years ago

An uncharged series RC circuit is to be connected across a battery. For each of the following changes, determine whether the tim

slavikrds [6]

a) Increase

b) Unchanged

c) Increase

Explanation:

The charge on a capacitor charging in a RC circuit connected to a battery follows the exponential equation:

$Q(t)=Q_0 (1-e^{-\frac{t}{RC}})$

where

$Q_0 = CV$ is the final charge stored in the capacitor, where C is the capacitance and V is the voltage of the battery

t is the time

R is the resistance of the circuit

The capacitor reaches 90% of its final charge when

$Q(t)=0.90Q_0$

Substituting and re-arranging the equation, we find:

$0.90Q_0 = Q_0(1-e^{-\frac{t}{RC}})\\0.90=1-e^{-\frac{t}{RC}}\\e^{-\frac{t}{RC}}=0.10\\-\frac{t}{RC}=ln(0.10)\\t=-RCln(0.10)=2.30RC$

We see that if we double the RC constant, then $(RC)'=2(RC)$

So the time taken will double as well:

$t'=2.30(RC)'=2.30(2RC)=2(2.30RC)=2t$

So, the answer is "increase"

In this second part, the battery voltage is doubled.

According to the equation written in part a),

$Q_0 =CV$

this means also that the final charge stored on the capacitor will also double.

However, the equation that gives us the time needed for the capacitor to reach 90% of its full charge is

$t=2.30 RC$

We see that this equation does not depend at all on the voltage of the battery.

Therefore, if the battery voltage is doubled, the final charge on the capacitor will double as well, but the time needed for the capacitor to reach 90% of its charge will not change.

So the correct answer is

"unchanged"

In this case, a second resistor is added in series with the original resistor of the circuit.

We know that for two resistors in series, the total resistance of the circuit is given by the sum of the individual resistances:

$R=R_1+R_2$

Since each resistance is a positive value, this means that as we add new resistors, the total resistance of the circuit increases.

Therefore in this problem, if we add a resistor in series to the original circuit, this means that the total resistance of the circuit will increase.

The time taken for the capacitor to reach 90% of its final charge is still

$t=2.30 RC$

As we can see, this time is directly proportional to the resistance of the circuit, R: therefore, if we add a resistor in series, the resistance of the circuit will increase, and therefore this time will increase as well.

So the correct answer is

"increase"

8 0

2 years ago

How much force is needed to accelerate a 20 kg mass at a rate of 4 m/s to the second power?

dusya [7]

Answer:

So 55 Newtons are needed.

6 0

2 years ago

Read 2 more answers

Photons with the highest energy have the ____

Setler79 [48]

Answer:

D. shortest wavelength

Explanation:

Photons with the highest energy have the shortest wavelength. The shorter the wavelength, the higher the energy of a photon.

A photon is a quantity that transmits electromagnetic energy from one place to the other.

Gamma rays have photons that transmits the highest amount of energy.
The rays have the shortest wavelength and highest frequency of all electromagnetic radiations.

Energy, wavelength and frequency of a photon are connected using the expression:

E = h f = $\frac{hc}{wavelength}$