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Sonbull [250]
2 years ago
13

a torch bulb is rated 2.5V and 750mA. Calculate its power,its resistance and the energy consumed if this bulb lighted for 4 hour

s
Physics
1 answer:
Hatshy [7]2 years ago
3 0
Using Ohm's Law, we can derived from this the value of resistance. If I=V/R, therefore, R = V/I
Substituting the values to the given, 
P = Power = ?
R = Resistance = ?
V = Voltage = 2.5 V
I = Current = 750 mA

R = V/I = 2.5/ (750 x 10^-3)
R = 3.33 ohms

Calculating the power, we have P = IV

P = (750 x 10^-3)(2.5) 
P = 1.875 W

The power consumption is the power consumed multiply by the number of hours. In here, we have;
1.875W x 4 hours = 7.5 watt-hours
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In a movie, Tarzan evades his captors by hiding under water for many minutes while breathing through a long, thin reed. Assume t
gladu [14]

Answer: 0.98m

Explanation:

P = -74 mm Hg = 9605 Pa = 9709N/m^2

= 9605 kg m/s^2/m^2

density of water: rho = 1 g/cc = 1 (10^-3 kg)/(10^-2 m)^-3 = 1000 kg/m^3

Pressure equation: P = rho g h

h = P/(rho g)

h = (9605 kg/m/s^2) / (1000 kg/m^3) / (9.8 m/s^2)

h = 0.98 m

0.98m is the maximum depth he could have been.

8 0
2 years ago
Anna applies a force of 19.5 newtons to push a book placed on a table. If the normal force of the book is 51.7 newtons, what is
GarryVolchara [31]

that would be given by

[email protected]

@ representing coefficient of kinetic friction.

thus 19.5/51.7 = 0.377

6 0
2 years ago
Sunlight strikes a piece of crown glass at an angle of incidence of 38.0°. Calculate the difference in the angle of refraction b
zhuklara [117]

Answer:

Difference in the angle of refraction = 0.3°

41.04° is the minimum angle of incidence.

Explanation:

Angle of incidence  = 38.0°

For yellow light :

Using Snell's law as:

\frac {sin\theta_2}{sin\theta_1}=\frac {n_1}{n_2}

Where,  

Θ₁ is the angle of incidence

Θ₂ is the angle of refraction

n₁ is the refractive index for yellow light which is 1.523

n₂ is the refractive index of air which is 1

So,  

\frac {sin\theta_2}{sin{38.0}^0}=\frac {1.523}{1}

{sin\theta_2}=0.9377

Angle of refraction for yellow light = sin⁻¹ 0.9377 = 69.67°.

For green light :

Using Snell's law as:

\frac {sin\theta_2}{sin\theta_1}=\frac {n_1}{n_2}

Where,  

Θ₁ is the angle of incidence

Θ₂ is the angle of refraction

n₁ is the refractive index for green light which is 1.526

n₂ is the refractive index of air which is 1

So,  

\frac {sin\theta_2}{sin{38.0}^0}=\frac {1.526}{1}

{sin\theta_2}=0.9395

Angle of refraction for green light = sin⁻¹ 0.9395 = 69.97°.

The difference in the angle of refraction = 69.97° - 69.67° = 0.3°

Calculation of the critical angle for the yellow light for the total internal reflection to occur :

The formula for the critical angle is:

{sin\theta_{critical}}=\frac {n_r}{n_i}

Where,  

{\theta_{critical}} is the critical angle

n_r is the refractive index of the refractive medium.

n_i is the refractive index of the incident medium.

n₁ is the refractive index for yellow light which is 1.523 (incident medium)  

n₂ is the refractive index of air which is 1 (refractive medium)

Applying in the formula as:

{sin\theta_{critical}}=\frac {1}{1.523}

The critical angle is = sin⁻¹ 0.6566 = 41.04°

5 0
2 years ago
A gold puck has a mass of 12 kg and a velocity of 5i – 4j m/s prior to a collision with a stationary blue puck whose mass is 18
Ugo [173]

Answer:

Explanation:D

6 0
2 years ago
A bullet starting from rest accelerates uniformly at a rate of 1,250 meters per square second. What is the bullet's speed after
Tatiana [17]

Answer:

125,000

Explanation:

8 0
2 years ago
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