A uniformly charged sphere has a potential on its surface of 450 V. At a radial distance of 7.2 m from this surface, the potential is150 V What is the radius of the sphere?

Respuesta :

Answer:

The radius of the sphere is 3.6 m.

Explanation:

Given that,

Potential of first sphere = 450 V

Radial distance = 7.2 m

If the potential of sphere =150 V

We need to calculate the radius

Using formula for potential

For 450 V

[tex]V=\dfrac{kQ}{r}[/tex]

[tex]450=\dfrac{kQ}{r}[/tex]....(I)

For 150 V

[tex]150=\dfrac{kQ}{r+7.2}[/tex]....(II)

Divided equation (I) by equation (II)

[tex]\dfrac{450}{150}=\dfrac{\dfrac{kQ}{r}}{\dfrac{kQ}{r+7.2}}[/tex]

[tex]3=\dfrac{(r+7.2)}{r}[/tex]

[tex]3r=r+7.2[/tex]

[tex]r=\dfrac{7.2}{2}[/tex]

[tex]r=3.6\ m[/tex]

Hence, The radius of the sphere is 3.6 m.

The radius of the sphere whose surface has a potential difference of  450 V is 3.6 m.

What is the radius of the sphere?

We know that the potential difference can be written as,

[tex]V = k\dfrac{Q}{R}[/tex]

We know that at  R= R, Potential difference= 450 V,

[tex]450 = k\dfrac{Q}{R}[/tex]

Also, at R = (R+7.2), Potential difference = 150 V,

[tex]150 = k\dfrac{Q}{(R+7.2)}[/tex]

Taking the ratio of the two,

[tex]\dfrac{450}{150} = \dfrac{kQ}{R} \times \dfrac{(R+7.2)}{kQ}\\\\\dfrac{450}{150} = \dfrac{(R+7.2)}{R}\\\\R = 3.6\ m[/tex]

Hence, the radius of the sphere whose surface has a potential difference of  450 V is 3.6 m.

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