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3 years ago

11

A classic demonstration illustrating eddy currents is performed by dropping a permanent magnet inside a conducting cylinder. The

magnet does not go into free fall. Instead it reaches terminal velocity and can take a few seconds to drop a length of about a meter. Suppose the mass of the magnet is 70 g and width of 1.0 cm. It falls with a terminal velocity of 10 cm/s and the length of the pipe is 80 cm. The magnitude of the Joule heating from the eddy currents is approximately:________

1 answer:

kvv77 [185]3 years ago

4 0

Answer:

The correct solution is "0.69 N".

Explanation:

The given values are:

Mass of magnet,

m = 70 g

or,

= 0.07 kg

Width,

= 1.0 cm

Velocity,

= 10 cm/s

Length of the pipe,

= 80 cm

Whenever the velocity is constant, then the net force which is acting on the magnet will be "0".

On the magnet,

The up-ward force will be:

⇒ $F=mg$

On substituting the values, we get

⇒ $=0.07\times 9.8$

⇒ $=0.69 \ N$

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[A] Write an expression for the equivalent resistance of three resistors connected in parallel.[ no derivation needed]

anzhelika [568]

Answer:

1) R1 + ((R2 × R3)/(R2 + R3))

2) 0.5 A

3) 3.6 V

Explanation:

1) We can see that resistors R2 and R3 are in parallel.

Formula for sum of parallel resistors; 1/Rt = 1/R2 + 1/R3

Making Rt the subject gives;

Rt = (R2 × R3)/(R2 + R3)

Now, Resistor R1 is in series with this sum of R2 and R3. Thus;

Total resistance of circuit = R1 + ((R2 × R3)/(R2 + R3))

2) R_total = R1 + ((R2 × R3)/(R2 + R3))

We are given;

R1 = 7.2 Ω

R2 = 8 Ω

R3 = 12 Ω

R_total = 7.2 + ((8 × 12)/(8 + 12))

R_total = 7.2 + 4.8

R_total = 12 Ω

Formula for current is;

I = V/R

I = 6/12

I = 0.5 A

3) since current through the circuit is 0.5 and R1 is 7.2 Ω.

Thus, potential difference through R1 is;

V = IR = 0.5 × 7.2 = 3.6 V

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2 years ago

You connect a 100-resistor, a 800-mH inductor, and a 10.0-uF capacitor in series across a 60.0-Hz, 120-V (peak) source. The impe

steposvetlana [31]

Answer:

Impedance, Z = 107 ohms

Explanation:

It is given that,

Resistance, R = 100 ohms

Inductance, $L=800\ mH=800\times 10^{-3}\ H=0.8\ H$

Capacitance, $C=10\ \mu F=10\times 10^{-6}\ F=10^{-5}\ F$

Frequency, f = 60 Hz

Voltage, V = 120 V

The impedance of the circuit is given by :

$Z=\sqrt{R^2+(X_C-X_L)^2}$ ...........(1)

Where

$X_C$ is the capacitive reactance, $X_C=\dfrac{1}{2\pi fC}$

$X_C=\dfrac{1}{2\pi \times 60\times 10^{-5}}=265.65\ \Omega$

$X_L$ is the inductive reactance, $X_L={2\pi fL}$

$X_L={2\pi \times 60\times 0.8}=301.59\ \Omega$

So, equation (1) becomes :

$Z=\sqrt{(100)^2+(265.65-301.59)^2}$

Z = 106.26 ohms

or

Z = 107 ohms

So, the impedance of the circuit is 107 ohms. Hence, this is the required solution.

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3 years ago

A piece of toast weighing 8 grams is flying through the air at 15

Ket [755]

The kinetic energy of toast is 0.06 J.

<u>Explanation:</u>

Kinetic energy is the way to determine the energy released when an object is in motion. In other times, it can be the energy required to move any object and to make it in motion.

As the mass of the toast is given as 8 g and speed is given as 15 m/s, if we ignore the friction caused by air molecules. Then the kinetic energy is the product of mass and square of velocity.

K.E. = $\frac{1}{2}$ × mass × v²

Kinetic energy = $\frac{1}{2} \times \frac{8}{1000} \times 15$

Since, the weight is given in grams , it needed to be converted into kg.

Kinetic energy = 0.06 J

Thus, the kinetic energy of toast is 0.06 J.

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3 years ago

Where do scientists believe the missing carbon is going? Why are they not sure?

White raven [17]

Answer: Scientists believe the missing carbon has found a sink in the Northern Forest. Scientist have come up with this idea because they believe consequences of global warming contributed to significant extent to the northern forest carbon sinking processes. In addition to that, scientists describe a process where the oceans of the world sink carbon to create a balance of the ecosystem. That is why they are not 100% sure.

Explanation:

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3 years ago

In the Hydrogen atom, the energy spacing between the is 4.07 x 101 J (Joules). When an is the frequency of the photons emitted?

agasfer [191]

Answer:

The frequency of the photon is $3.069\times10^{14}\ Hz$ .

Explanation:

Given that,

Energy $E=4.07\times10^{-19}\ J$

We need to calculate the energy

Using relation of energy

$E_{4}-E_{2}=\Delta E$

Where, $\Delta E$ = energy spacing

$4h\nu-2h\nu=4.07\times10^{-19}$

$\nu=\dfrac{4.07\times10^{-19}}{2h}$

Put the value of h into the formula

$\nu=\dfrac{4.07\times10^{-19}}{2\times6.63\times10^{-34}}$

$\nu=3.069\times10^{14}\ Hz$

Hence, The frequency of the photon is $3.069\times10^{14}\ Hz$ .

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3 years ago