Hi Vivek,

I've gone through your requirement, Hope below code will help you:--->

Apex trigger:-->

trigger SendEmailToParent on Contact (after insert) 
{
   if(Trigger.isAfter && Trigger.isInsert)
   {
       SendEmailToParentClass.sendingEmail(Trigger.New);
   }
}

Apex Class :-->

public class SendEmailToParentClass
{
    public static void sendingEmail(List<Contact> allContact)
    {
        try
        {
            Set<Id> allPhyscianId=new Set<Id>();
            for(Contact opp:allContact)
            {
                allPhyscianId.add(opp.Physician__c);
            }
            
            List<Physician __c> allPhyscians=new List<Physician __c>([select id,EmailField__c from Physician __c where Id IN:allPhyscianId]);
            
            for(Physician __c physcian:allPhyscians)
            {
                List<Messaging.SingleEmailMessage> emails = new List<Messaging.SingleEmailMessage>();   
                
                string Parentemail = '';
                string accName = '';
                string emailbody = '';
                
                accName = physcian.Name;
                Parentemail = physcian.EmailField__c;
                
                
                Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
                mail.setSaveAsActivity(false);
                
                mail.setSubject('Mail Subject');//Your Subject Of Email
                
                mail.setHtmlBody('Your Email Body');//Your Email Body
                mail.toAddresses = new String[] {Parentemail};
                    mail.setTreatTargetObjectAsRecipient(false);
                emails.add(mail);
            }            
            
        
        
        Messaging.SendEmailResult[] result =Messaging.sendEmail(emails);
        
    }
    
    
    catch(Exception e)
    {
        System.debug('Error in-->'+e.getLineNumber()+' and Error is='+e.getMessage());
    }
}
}

I hope you find the above solution helpful. If it does, please mark as Best Answer to help others too.

Thanks and Regards,
Deepali Kulshrestha
www.kdeepali.com