# Physics 2 question?

Consider the figure shown below. Q1 = 3.00 ×10−9 C and Q2 = -8.80 ×10−9 C. Calculate the potential at the location marked '3'. Charges Q1, Q2, and point '3' are all located at integer coordinates, and assume the potential is zero at infinity. Relevance

The electric potential Vₑ from a charge Q at a distance r is given by Vₑ = kQ/r, where k is the Coulomb constant: 8.99 × 10⁹ N·m²/C².

The distance r₁ from Q₁ to point 3 is √(2²+4²) = √20 cm ≈ 4.47 cm, or 0.0447 m, or 4.47 × 10ˉ² m.

So the potential at point 3, from Q₁, is

kQ₁/r₁ = (8.99 × 10⁹ N·m²/C²)(3.00 × 10ˉ⁹ C) / (4.47 × 10ˉ² m)

= 6.03 × 10² N·m/C

= 6.03 × 10² J/C

= 6.03 × 10² V, or 603 V.

The distance r₂ from Q₂ to point 3 is √(6²+3²) = √45 cm ≈ 6.708 cm, or 0.06708 m, or 6.708 × 10ˉ² m.

So the potential at point 3, from Q₂, is

kQ₂/r₂ = (8.99 × 10⁹ N·m²/C²)(-8.80 × 10ˉ⁹ C) / (6.708 × 10ˉ² m)

= -1.18 × 10³ V, or -1180 V.

These potentials are scalars, so they simply add algebraically:

603 V + (-1180 V) = -577 V.

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•  Q1 = 3.00 ×10−9 C and Q2 = -8.80 ×10−9 C ?? those numbers make no sense

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Lv 7
2 months agoReport

They make sense if you realize that the "-9" numbers are intended to be exponents: 10ˉ⁹.

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