To find the capacitance of a conical capacitor in relation to the electric field and voltage, you can use the following equations:

1. Electric Field (E): The electric field in the conical capacitor can be expressed in terms of the voltage and the geometry of the capacitor: $E = -\frac{dV}{dr}$ where $V$ is the voltage across the capacitor.

2. Voltage (V): The voltage can be determined by integrating the electric field: $V = -\int_{r_a}^{r_b} E \, dr$

3. Capacitance (C): The capacitance is defined as the charge stored per unit voltage: $C = \frac{Q}{V}$ where $Q$ is the charge. For a conical capacitor, the charge can be related to the electric field and the area of the electrodes.

4. Charge Density (σ): The charge density can be expressed in terms of the electric field: $\sigma = \varepsilon_0 E$ where $\varepsilon_0$ is the permittivity of free space.

5. Relation of Capacitance to Geometry: For a conical capacitor, the capacitance can be influenced by its geometric parameters: $C = \frac{\varepsilon_0 A}{d}$ where $A$ is the effective area of the capacitor surfaces and $d$ is the distance between the electrodes.

Steps to Solve for Capacitance

1. Determine the electric field $E$ using the voltage.
2. Integrate $E$ to find $V$.
3. Use the charge density to relate charge $Q$ and capacitance $C$.

Further Considerations

• Geometric Parameters: Ensure you accurately account for the cone’s dimensions, including $r_a$, $r_b$, $\theta_+$, and $\theta_-$.
• Integration Limits: When integrating for voltage, use the appropriate limits based on the capacitor’s geometry.

Would you like further details on any of these equations or how to apply them specifically to your problem?

Here are some questions you might consider next:

1. How do the angles $\theta_+$ and $\theta_-$ affect the electric field distribution?
2. What assumptions can be made about the electric field in a conical capacitor?
3. How would you derive the effective area $A$ for the conical surfaces?
4. Can you describe the relationship between charge density and electric field for this geometry?
5. What role does the permittivity of the dielectric material play in the capacitance?

Tip: Always visualize the geometry of the capacitor when working with non-standard shapes, as this can greatly aid in understanding the electric field and potential distribution.