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3 years ago

15

Find the resistance of an electric light bulb if a current of 0.08 A flows when the potential difference across the bulb is 120

V.

1 answer:

lora16 [44]3 years ago

8 0

U=RI Ohm's law
then R=U/I
=120/0.08
=2250Ω
hope this helps you

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The ammonia molecule (NH3) has a dipole moment of 5.0×10?30C?m. Ammonia molecules in the gas phase are placed in a uniform elect

Neko [114]

Question (continuation)

(a) What is the change in electric potential energy when the dipole moment of a molecule changes its orientation with respect to E S from parallel to perpendicular?

(b) At what absolute temperature T is the average translational kinetic energy 3/2kT of a molecule equal to the change in potential energy calculated in part (a)?

Answer:

a. 9.0 * 10^-24 Joules

b. 0.44K

Explanation:

Given

Let p = dipole moment = 5.0 * 10^-30 Cm

Let E = Magnitude = 1.8 * 10^6 N/m

a.

The charge in electric potential = Final Charge - Initial Charge

Initial Charge = Potential Energy

Initial Energy = -pE cosФ where Ф = 0

So, initial Energy = - 5.0 * 10^-30 * 1.8 * 10^6

Initial Energy = -9 * 10^-24 Joules

Final Energy = 0

Charge = 0 - (-9.0 * 10^-24)

Charge = 9.0 * 10^-24 Joules

b.

Absolute Temperature

Change in Kinetic Energy = Change in Potential Energy = 9.0 * 10^-24

Change in Kinetic Energy = 3/2kT where k is Steven-Boltzmann constant = 1.38 * 10^-23

So,

9.0 * 10^-24 = 3/2 * 1.38 * 10^-23 * T

T = (9.0 * 10^-24 * 2)/(3 * 1.38 * 10^-23)

T = (18 * 10^-24)/(4.14 * 10^-23)

T = 0.44K

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3 years ago

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JulsSmile [24]

Oil, grease and dry lubricants

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3 years ago

A force of 60 N is applied to a skier to pull him along a horizontal surface so that his speed remains constant. If the coeffici

matrenka [14]

Answer:

$1200\ \text{N}$

Explanation:

F = Force on the skier = 60 N

$\mu$ = Coefficient of friction = 0.05

w = Weight of skier

Force is given by

$F=\mu w$

$\Rightarrow w=\dfrac{F}{\mu}$

$\Rightarrow w=\dfrac{60}{0.05}=\dfrac{6000}{5}$

$\Rightarrow w=1200\ \text{N}$

Weight of the skier on which the force is being applied is $1200\ \text{N}$ .

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3 years ago

An electron moves in a region where the magnetic field is uniform and has a magnitude of 80 μT. The electron follows a helical p

sladkih [1.3K]

Answer:

3.4 x 10⁴ m/s

Explanation:

Consider the circular motion of the electron

B = magnetic field = 80 x 10⁻⁶ T

m = mass of electron = 9.1 x 10⁻³¹ kg

v = radial speed

r = radius of circular path = 2 mm = 0.002 m

q = magnitude of charge on electron = 1.6 x 10⁻¹⁹ C

For the circular motion of electron

qBr = mv

(1.6 x 10⁻¹⁹) (80 x 10⁻⁶) (0.002) = (9.1 x 10⁻³¹) v

v = 2.8 x 10⁴ m/s

Consider the linear motion of the electron :

v' = linear speed

x = horizontal distance traveled = 9 mm = 0.009 m

t = time taken = $\frac{2\pi m}{qB}$ = $\frac{2\pi (9.1\times 10^{-31})}{(1.6\times 10^{^{-19}})(80\times 10^{-6})}$ = 4.5 x 10⁻⁷ sec

using the equation

x = v' t

0.009 = v' (4.5 x 10⁻⁷)

v' = 20000 m/s

v' = 2 x 10⁴ m/s

Speed is given as

V = sqrt(v² + v'²)

V = sqrt((2.8 x 10⁴)² + (2 x 10⁴)²)

v = 3.4 x 10⁴ m/s

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3 years ago

Which of the following statements about stellar parallax is true?

iren2701 [21]

Answer:

The second option : The closer a star is to us, the more parallax it exhibits.

Explanation:

When a star is close to the observer, it is possible to better see the difference in movement and distant because of space behind or other stars close to it, so we can measure distances from these celestial bodies by using parallax. Just as trees seem to move more than the mountains in the background during a car trip, so do stars, but in a much more imperceptible way. The closer to the viewer the more parallax will display.

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2 years ago