Unity Script Reference:

Rigidbody.AddRelativeTorque

AddRelativeTorque(torque: Vector3, mode: ForceMode = ForceMode.Force): void;

void AddRelativeTorque(Vector3 torque, ForceMode mode = ForceMode.Force);

def AddRelativeTorque(torque as Vector3, mode as ForceMode = ForceMode.Force) as void

Description

Adds a torque to the rigidbody relative to the rigidbodie's own coordinate system.

As a result the rigidbody will start spinning around the torque axis.

	// Spins the rigidbody around its own y-axis	function FixedUpdate () {
		rigidbody.AddRelativeTorque (Vector3.up * 10);
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void FixedUpdate() {
        rigidbody.AddRelativeTorque(Vector3.up * 10);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def FixedUpdate() as void:
		rigidbody.AddRelativeTorque((Vector3.up * 10))

AddRelativeTorque(x: float, y: float, z: float, mode: ForceMode = ForceMode.Force): void;

void AddRelativeTorque(float x, float y, float z, ForceMode mode = ForceMode.Force);

def AddRelativeTorque(x as float, y as float, z as float, mode as ForceMode = ForceMode.Force) as void

Description

Adds a torque to the rigidbody relative to the rigidbodie's own coordinate system.

As a result the rigidbody will start spinning around the torque axis.

	// Spins the rigidbody around its own y-axis	function FixedUpdate () {
		rigidbody.AddRelativeTorque (0, 10, 0);
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void FixedUpdate() {
        rigidbody.AddRelativeTorque(0, 10, 0);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def FixedUpdate() as void:
		rigidbody.AddRelativeTorque(0, 10, 0)

If you want to apply a force over several frames you should apply it inside FixedUpdate instead of Update.