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3 years ago

How many neutrons does element X have if its atomic number is 39 and its mass number is 79?

Physics

1 answer:

bazaltina [42]3 years ago

6 0

Number of neutrons: atomic mass - atomic number

Element X's atomic mass is 79 and its atomic number is 39. Subtract 39 from 79 to find how many neutrons Element X has.

79 - 39 = 40

Element X has 40 neutrons.

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A 40-W lightbulb is 1.7 m from a screen. What is the intensity of light incident on the screen? Assume that a lightbulb emits ra

Sonja [21]

Answer:

Intensity, $I=1.101\ W/m^2$

Explanation:

Power of the light bulb, P = 40 W

Distance from screen, r = 1.7 m

Let I is the intensity of light incident on the screen. The power acting per unit area is called the intensity of the light. Its formula is given by :

$I=\dfrac{P}{A}$

$I=\dfrac{P}{4\pi r^2}$

$I=\dfrac{40\ W}{4\pi (1.7\ m)^2}$

$I=1.101\ W/m^2$

So, the intensity of light is $1.101\ W/m^2$ .

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Answer:

a) 1m

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c) 3mm

Explanation:

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3 years ago

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A capacitor consists of two metal surfaces separated by an insulating layer. A new capacitor has no charge on either of its surf

mihalych1998 [28]

<h2>Answer:</h2><h3>(A) the positively charged surface increases and the energy stored in the capacitor increases.</h3>

When charging a capacitor transferring charge from one surface to the other, the first surface becomes negatively charged while the second surface becomes positively charged. As you transfer the charge, the voltage of the positively charged surface increases and the energy stored in the capacitor also increases. We can solve this by the definition of <em>capacitance</em><em> </em>that is <em>a measure of the ability of a capacitor to store energy. </em>For any capacitor, the capacitance is a constant defined as:

$C=\frac{Q}{V_{ab}}$

To maintain $C$ constant, if Q increases V also increases.

On the other hand, the potential energy $U$ can be expressed as:

$U=\frac{Q^{2}}{2C}$

In conclusion, as Q increases the potential energy also increases.

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3 years ago

a particle moves with simple harmonic motion.if it's acceleration is 100 times it's displacement what is it's period

Liono4ka [1.6K]

Answer:

Simple harmonic motion is repetitive. The period T is the time it takes the object to complete one oscillation and return to the starting position. ... If at t = 0 the object has its maximum displacement in the positive x-direction, then φ = 0, if it has its maximum displacement in the negative x-direction, then φ = π.

Explanation:

Simple harmonic motion, in physics, repetitive movement back and forth through an equilibrium, or central, position, so that the maximum displacement on one side of this position is equal to the maximum displacement on the other side

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3 years ago