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2 years ago

In Burglar alarm LDR acts as a/an a. off switch b. on switch c. AND gate d. OR gate

Physics

1 answer:

Gelneren [198K]2 years ago

4 0

In Burglar alarm, LDR acts an AND gate.

Answer: C

Explanation

The LDR is light dependent resistor. The principle used in the working of LDR is that the resistance is inversely proportional to the intensity of light falling on the diode.

In burglar alarm, LDR diode is combined with an IC 555.

Normally an LED source is made to be incident on the LDR diode with same intensity such that the resistance will be maintained constant.

As the LDR is connected with IC, the voltage will be high when light is falling on the diode.

The IC will give only two output states that is high and low. This confirms that LDR in burglar alarm act as AND gate.

As the thief enters and crosses the LED light, the intensity of the light falling on the diode will decrease leading to decrease in the voltage which will cause the alarm to beep.

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Which letter correctly identifies the part of the hydrologic cycle that is most directly affected by impervious building materia

masha68 [24]

Infiltration

Explanation:

The component of the hydrologic cycle affected by impervious building such as concrete and asphalt is infiltration.

Water infiltration is a major component of the hydrologic cycle.
Concretes and other materials can prevent water from going down into the earth.
This affects the ground water system in place.
It leads to increase in surface run off and might cause inundation of an area.
Infiltration is a very important component of water cycle.
It takes water to plant root and recharges groundwater systems.
Impervious structures takes this capability away.

learn more:

Biogeochemical cycle brainly.com/question/3509510

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3 0

2 years ago

Two disks with the same rotational inertia i are spinning about the same frictionless shaft, with the same angular speed ω, but

valentina_108 [34]

Answer:

3. none of these

Explanation:

The rotational kinetic energy of an object is given by:

$K=\frac{1}{2}I \omega^2$

where

I is the moment of inertia

$\omega$ is the angular speed

In this problem, we have two objects rotating, so the total rotational kinetic energy will be the sum of the rotational energies of each object.

For disk 1:

$K_1 = \frac{1}{2}I (\omega)^2 = \frac{1}{2}I\omega^2$

For disk 2:

$K_2 = \frac{1}{2}I(-\omega)^2 = \frac{1}{2}I\omega^2$

so the total energy is

$K=K_1 + K_2 = \frac{1}{2}I\omega^2 + \frac{1}{2}I\omega^2 = I\omega^2$

So, none of the options is correct.

5 0

2 years ago

A resistor R1 is wired to a battery, then resistor R2 is added in series. Are (a) the potential difference across R1 and (b) the

tia_tia [17]

Answer:

Explanation:

a ) Earlier emf of cell applied on R₁ but now emf will be distributed among R₁ and R₂

Potential difference on R₁ will become less .

b ) Current is inversely proportional to resistance of the circuit. As resistance increases , current will be less . So current through R₁ will become less.

c )

When resistance is added in series , they are added up to obtain equivalent resistance . So equivalent resistance R₁₂ will be more than R₁ OR R₂.

6 0

2 years ago

A spaceship flies from Earth to a distant star at a constant speed. Upon arrival, a clock on board the spaceship shows a total e

m_a_m_a [10]

Answer:

35 288 mile/sec

Explanation:

This is a problem of special relativity. The clocks start when the spaceship passes Earth with a velocity v, relative to the earth. So, out and back from the earth it will take:

$10 years = \frac{2d}{v}$

If we use the Lorentz factor, then, as observed by the crew of the ship, the arrival time will be:

$0.8 = \sqrt{1-\frac{v^{2} }{c^{2} } }$

Then the amount of time wil expressed as a reciprocal of the Lorentz factor. Thus:

$0.8 = \sqrt{1 - \frac{v^{2} }{c^{2} } }$

$0.64 = 1-\frac{v^{2} }{186282^{2} }$

solving for v, gives = 35 288 miles/s

4 0

2 years ago

Susan and Hannah are each riding a swing. Susan has a mass of 25 kilograms, and Hannah has a mass of 30 kilograms. Susan’s swing

Charra [1.4K]

Answer:

Kinetic energy is given by:

K.E. = 0.5 m v²

Susan has mass, m = 25 kg

Velocity with which Susan moves is, v = 10 m/s

Hannah has mass, m' = 30 kg

Velocity with which Hannah moves is, v' = 8.5 m/s

Kinetic energy of Susan:

0.5 m v² = 0.5 × 25 kg × (10 m/s)² = 1250 J

Kinetic energy of Hannah:

0.5 m v'² = 0.5 × 30 kg × (8.5 m/s)² = 1083.75 J

Susan's kinetic energy is 1250 J and Hannah's kinetic energy is 1083.75 J.

Since kinetic energy is dependent on mass and square of speed. Thus, speed has a greater effect than mass. As it is evident from the above example. Susan has greater kinetic energy due to higher speed than Hannah.

4 0

2 years ago