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What is the magnitude of the electric field at the point \((3.00 \hat{\mathrm{i}}-2.00 \hat{\mathrm{j}}+4.00 \hat{\mathrm{k}}) \mathrm{m}\) if the electric potential is given by \(V=\) \(2.00 x y z^{2}\), where \(V\) is in volts and \(x, y\), and \(z\) are in meters?

Short Answer

Expert verified
The electric field magnitude is approximately 150.09 V/m.

Step by step solution

01

Understand the Problem

The problem asks for the magnitude of the electric field at a specific point in space, given an electric potential function. The electric field is related to the electric potential by the negative gradient of the potential.
02

Determine the Gradient Operator

The gradient of a scalar field, such as the electric potential, is a vector field that points in the direction of the greatest rate of increase of the potential. For a function of three variables \(V(x, y, z)\), the gradient is given by:\( abla V = \left( \frac{\partial V}{\partial x}, \frac{\partial V}{\partial y}, \frac{\partial V}{\partial z} \right) \).
03

Compute Partial Derivatives

Compute the partial derivatives of \(V(x, y, z) = 2.00 x y z^2\):- \(\frac{\partial V}{\partial x} = 2.00 y z^2\)- \(\frac{\partial V}{\partial y} = 2.00 x z^2\)- \(\frac{\partial V}{\partial z} = 4.00 x y z\).
04

Evaluate Gradient at Given Point

Substitute the point \((x, y, z) = (3.00, -2.00, 4.00)\) into the gradient expressions:- \(\frac{\partial V}{\partial x} = 2.00(-2.00)(4.00^2) = 2.00 \times (-2.00) \times 16 = -64.00 \)- \(\frac{\partial V}{\partial y} = 2.00(3.00)(4.00^2) = 2.00 \times 3.00 \times 16 = 96.00 \)- \(\frac{\partial V}{\partial z} = 4.00(3.00)(-2.00)(4.00) = 4.00 \times 3.00 \times (-2.00) \times 4.00 = -96.00 \).
05

Determine Electric Field Vector

The electric field \(\mathbf{E}\) is the negative of the gradient of \(V\):\( \mathbf{E} = -abla V = (-(-64.00), -(96.00), -(-96.00)) = (64.00, -96.00, 96.00) \).
06

Compute Magnitude of Electric Field

The magnitude of the electric field vector \(\mathbf{E} = (64.00, -96.00, 96.00)\) is:\[ |\mathbf{E}| = \sqrt{64.00^2 + (-96.00)^2 + 96.00^2} = \sqrt{4096 + 9216 + 9216} = \sqrt{22528} \approx 150.09 \].
07

Conclusion

Thus, the magnitude of the electric field at the given point is approximately 150.09 V/m.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Electric Potential
Electric potential is the measure of the potential energy per unit charge at a specific point in an electric field. It is represented by the symbol \(V\) and is measured in volts. Imagine it like a hill where charges 'roll'. The higher you are on the hill, the more potential energy you have. In this exercise, the electric potential is defined as \(V = 2.00xyz^2\).
This tells us how the potential changes with variations in \(x\), \(y\), and \(z\). Each of these variables plays a role in determining the energy landscape, like crafting the slopes and ridges on our 'hill'.
  • x, y, z represent position in space, and each has an effect on potential.
  • The equation shows potential increasing with \(xy\) and particularly powerful with \(z^2\).
Understanding and calculating electric potential is crucial for grasping how electric fields influence charged particles.
Gradient
The gradient of a field points in the direction of the largest space-related increase of that field. Think of it as the steepest path on our energy 'hill'. The gradient helps us understand how rapidly and in what direction the potential differs.
In mathematical terms, for the potential \(V(x, y, z)\), the gradient is represented as \(abla V = \left( \frac{\partial V}{\partial x}, \frac{\partial V}{\partial y}, \frac{\partial V}{\partial z} \right)\). This captures the rate of change across each axis:
  • \(\frac{\partial V}{\partial x}\): Rate of change of potential along the x-axis.
  • \(\frac{\partial V}{\partial y}\): Rate of change along the y-axis.
  • \(\frac{\partial V}{\partial z}\): Effect along the z-axis.
The gradient serves as a bridge to finding the electric field from the potential.
Partial Derivative
Partial derivatives illustrate how a function changes with respect to one variable alone, holding others constant. This is like examining how our 'hill' steeply rises or falls when moving solely in one direction, unaffected by changes elsewhere.
For the potential \(V = 2.00xyz^2\), the partial derivatives are:
  • \(\frac{\partial V}{\partial x} = 2.00yz^2\).
  • \(\frac{\partial V}{\partial y} = 2.00xz^2\).
  • \(\frac{\partial V}{\partial z} = 4.00xyz\).
These expressions show how potential changes along each axis. Mastering the concept of partial derivatives helps in understanding gradients and ultimately the electric field dynamics.
Knowing these values at a certain point, which we calculate in the exercise, is crucial for practical applications in physics.
Electric Field Magnitude
The magnitude of the electric field tells you about the strength of the field at a given point. This is similar to measuring how fast and powerfully an object might be pushed off our 'hill'. The electric field vector \(\mathbf{E}\) can be derived from the negative gradient of the potential: \(\mathbf{E} = -abla V\).
From the gradient, substitute our calculated partial derivatives and negate them:
  • At our given point, \(abla V\) resulted in \( (64.00, -96.00, 96.00) \).
  • Then electric field \(\mathbf{E} = (64.00, -96.00, 96.00)\).
The magnitude of this vector is calculated using Pythagoras' theorem:\(|\mathbf{E}| = \sqrt{64.00^2 + (-96.00)^2 + 96.00^2} \approx 150.09 \text{ V/m}\).
This magnitude provides insight into the field's intensity, fundamental for predicting how charged particles move within the field.

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Most popular questions from this chapter

What are (a) the charge and (b) the charge density on the surface of a conducting sphere of radius \(0.15 \mathrm{~m}\) whose potential is \(200 \mathrm{~V}\) (with \(V=0\) at infinity)?

The electric potential \(V\) in the space between two flat parallel plates 1 and 2 is given (in volts) by \(V=1500 x^{2}\), where \(x\) (in meters) is the perpendicular distance from plate \(1 .\) At \(x=1.3 \mathrm{~cm},(\mathrm{a})\) what is the magnitude of the electric field and \((b)\) is the field directed toward or away from plate \(1 ?\)

In the quark model of fundamental particles, a proton is composed of three quarks: two "up" quarks, each having charge \(+2 e / 3\), and one "down" quark, having charge \(-e / 3\). Suppose that the three quarks are equidistant from one another. Take that separation distance to be \(1.32 \times 10^{-15} \mathrm{~m}\) and calculate the electric potential energy of the system of (a) only the two up quarks and (b) all three quarks.

Two large, parallel, conducting plates are \(12 \mathrm{~cm}\) apart and have charges of equal magnitude and opposite sign on their facing surfaces. An electrostatic force of \(3.9 \times 10^{-15} \mathrm{~N}\) acts on an electron placed anywhere between the two plates. (Neglect fringing.) (a) Find the electric field at the position of the electron. (b) What is the potential difference between the plates?

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