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3 years ago

What must a magnet always have?

Physics

2 answers:

ohaa [14]3 years ago

8 0

Answer:

the anwser is d

Explanation:

you must have a north and south pole

Mazyrski [523]3 years ago

8 0

Answer:

your anwser would be

D) two opposite poles

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PLEASE HELP!!!!!!!!

ivanzaharov [21]

Answer:

the is D

Explanation:

An action-reaction force pair

6 0

3 years ago

Read 2 more answers

A 20 watt light bulb is left burning inside a refrigerator operating on a reverse Carnot cycle. If the refrigerator also draws 2

Gwar [14]

Explanation:

Given that,

Power drawn by the refrigerator = 20 watt

Power of burning light inside = 20 watt

Room temperature = 27°C

We need to calculate the temperature

Using formula of coefficient of refrigerator

$COR_{R}=\dfrac{Q_{c}}{W}$

$\dfrac{Q_{c}}{W}=\dfrac{T_{c}}{T_{H}-T_{c}}$

Put the value into the formula

$\dfrac{20}{20}=\dfrac{T_{c}}{T_{H}-T_{c}}$

$\dfrac{T_{c}}{T_{H}-T_{c}}=1$

$T_{h}=2T_{c}$

$T_{c}=\dfrac{T_{h}}{2}$

$T_{c}=\dfrac{27+273}{2}$

$T_{c}=150\ K$

$T_{c}$ is less than $T_{h}$

Therefore, refrigerator cools its interior below room temperature while the bulb is on.

Hence, This is the required solution.

8 0

4 years ago

You want to use the idea of electromagnetic induction to make the bulb in your small flashlight glow; it glows when the potentia

makkiz [27]

a) 57.5 m/s

b) Yes

Explanation:

According to Faraday-Newmann-Lenz's law, the electromotive force induced in the coil due to the change in magnetic flux through it is given by:

$\epsilon=-\frac{N \Delta \Phi}{\Delta t}$

where

N is the number of turns in the coil

$\Delta \Phi$ is the change in magnetic flux

$\Delta t$ is the time interval

The change in magnetic flux can be written as

$\Delta \Phi = A\Delta B$

where

A is the area of the coil

$\Delta B$ is the variation of the strength of the magnetic field

Re-writing the equation,

$\epsilon=-\frac{NA\Delta B}{\Delta t}$

To make the bulb glowing, the induced emf must be:

$\epsilon=1.5 V$

And we also have:

N = 100

$\Delta B=0 T-3.6\cdot 10^{-2} T=-0.036 T$

$A=2.9\cdot 10^{-4} m^2$

So we can find the maximum time required to induce this emf:

$\Delta t=-\frac{NA\Delta B}{\epsilon}=-\frac{(100)(2.9\cdot 10^{-4})(-0.036)}{1.5}=6.96\cdot 10^{-4} s$

Since the length to cover in this time is

L = 4.0 cm = 0.04 m

The speed should be

$v=\frac{L}{t}=\frac{0.04}{6.96\cdot 10^{-4}}=57.5 m/s$

Yes: if the coil is moved at a speed of 57.7 m/s, then the potential difference induced in the bulb will be 1.5 V, which is enough to make the bulb glowing.

6 0

3 years ago

Two general points to remember for recovering from skids are: keep your eyes pointed in the direction you want to go and you wil

Semmy [17]

The answer is do not break, the key avoiding skids is to always smoothly apply your brakes and accelerator and to turn slowly and smoothly. Reducing of the speed before oncoming turns and once driving in possibly hazardous circumstances such as wet, icy or snow covered roadways or on roadways with loose gravel.

8 0

4 years ago

Why do different atoms or molecules preferentially absorb different wavelengths of light?

Paladinen [302]

Answer:

The electrons in an atom can only occupy certain allowed energy levels. ... Only certain energy levels are allowed, so only certain transitions are possible and hence specific wavelengths are emitted when an electron drops to a lower energy level.

6 0

3 years ago